I've extracted the details from the links provided by Geetha and Aditya, and am posting the complete list of Backward and Scheduled castes from TN below.
List of Backward Classes approved by Government of Tamil Nadu
1. BACKWARD CLASSES
Agamudayar including Thozhu or Thuluva Vellala
Agaram Vellan Chettiar
Alwar, Azhavar and Alavar (in Kanniyakumari District and Shencottah Taluk of Tirunelveli District.)
Servai(except Tiruchirapalli, Karur, Perambalur and Pudukottai Districts.)
Ansar
Arayar, Nulayar(in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Archakarai Vellala
Aryavathi(in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Ayira Vaisyar
Badagar
Billava
Bondil
Boyas (except Tiruchirapalli, Karur, Perambalur, Pudukottai, The Nilgiris, Salem , Namakkal and Dharmapuri Districts). Pedda Boyar (except Tiruchirapalli, Karur , Perambalur and Pudukottai Districts) Oddars (except Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli, Karur, Perambalur, Pudukottai, Madurai,Theni and Dindigul Districts) Kaloddars (except Kancheepuram, Tiruvallur, Ramanathapuram, Sivaganga, Virudhunagar, Madurai, Theni, Dindigul, Pudukottai, Tiruchirapalli, Karur Perambalur, Tirunelveli, Thoothukudi, Salem and Namakkal Districts) Nellorepet oddars (except Vellore and Tiruvannamalai Districts) Sooramari oddars ( except Salem and Namakkal Districts)
Chakkala (except Sivaganga, Virudhunagar, Ramanathapuram,Thanjavur Nagapattinam, Tiruvarur, Pudukottai, Tiruchirapalli, Karur, Perambalur, Madurai, Theni, Dindigul and the Nilgiris Districts)
Chavalakarar (in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Chettu or Chetty (including Kottar Chetty, Elur Chetty, Pathira Chetty,Valayal Chetty,Pudukadai Chetty ) ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Chowdry
Converts to Christianity from Scheduled Castes irrespective of the generation of conversion for the purpose of reservation of seats in Educational Institutions and for seats in Public Services
C.S.I formerly S.I.U.C (in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Donga Dasaris (except Kancheepuram, Tiruvallur, Tiruchirapalli,Karur, Perambalur, Pudukottai Chennai ,Salem and Namakkal Districts)
Dekkani Muslims
Devangar, Sedar
Dombs (except Pudukottai, Tiruchirapalli ,Karur and Perambalur Districts) Dommars (except Thanjavur, Nagapattinam,Tiruvarur, Pudukottai, Vellore and Thiruvannamalai Districts)
Dudekula
Enadi
Ezhavathy(in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Ezhuthachar (in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Ezhuva(in Kanniyakumari District and Shencottah Taluk of Tirunelveli District)
Gangavar
Gavara, Gavarai and Vadugar(Vaduvar)(other than Kamma, Kapu,Balija and Reddi)
Gounder
Gowda (including Gammala, Kalali and Anuppa Gounder)
Hegde
Idiga
IllathuPillaimar, Illuvar, Ezhuvar and Illathar
Jhetty
Jogis (Except Kancheepuram, Tiruvallur, Madurai, Theni, Dindigul Cuddalore, Villupuram, Vellore and Tiruvannamalai Districts)
Kabbera
Kaikolar, Sengunthar
Kaladi (except Sivaganga, Virudhunagar, Ramanatha puram, Madurai,Theni,Dindigul,Thanjavur, Nagapattinam,Tiruvarur, Pudukottai, Tiruchirapalli, Karur and Perambalur Districts)
Kalari Kurup including Kalari Panicker (in Kanniyakumari District and Shenkottah Taluk of Tirunelveli District)
Kalingi
Kallar, Easanattu kallar, Gandharva Kottai Kallars(except Thanjavur, Nagapattinam, Tiruvarur and pudukottai Districts) Kootappal Kallars-(except Pudukottai, Tiruchirapalli, Karur and Perambalur Districts) Piramalai Kallars- (except Sivaganga,Virudhunagar, Ramanathapuram. Madurai. Theni, Dindigul, Pudukottai, Thanjavur, Nagapattinam and Tiruvarur Districts)Periyasooriyur Kallars- (except Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Kallar Kula Thondaman
Kalveli Gounder
Kambar
Kammalar or Viswakarma , Viswakarmala (including Thattar, Porkollar, Kannar, Karumar, Kollar, Thacher, Kal Thacher, Kamsala and Viswa brahmin.
Kani, Kanisu, Kaniyar Pannikar
Kaniyala Vellalar
Kannada Saineegar ,Kannadiyar (Throughout the State) and Dasapalanjika (Coimbatore, Erode and the Nilgiris Districts)
Kannadiya Naidu
Karpoora Chettiar
Karuneegar (Seer Karuneegar, Sri Karuneegar, Sarattu Karuneegar, Kaikatti Karuneegar, Mathuvazhi Kanakkar, Sozhi Kanakkar, and Sunnambu Karuneegar)
Kasukkara Chettiar
Katesar, Pattamkatti
Kavuthiyar
Kerala Mudali
Kharvi
Khatri
Kongu Vaishnava
Kongu Vellalars( including Vellala Gounder, Nattu Gounder, Narambukkatti Gounder, Tirumudi Vellalar, Thondu Vellalar, Pala Gounder, Poosari, Gounder, Anuppa Vellala Gounder, Kurumba Gounder, Padaithalai Gounder, Chendalai Gounder, Pavalankatti Vellala Gounder, Pallavellala GounderSanku,Vellala Gounder,and Rathinagiri Gounder).
KoppalaVelama
Koteyar
Krishnanvaka (in Kanniyakumari District and Shenkottah Taluk of Tirunelveli District)
Kudikara Vellalar
Kudumbi ( in Kanniyakumari District and Shenkottah Taluk of Tirunelveli District)
Kuga Vellalar
Kunchidigar
Labbais including Rowthar and Marakayar (whether their spoken language is Tamil or Urdu)
Lambadi
Latin Catholics (in Kanniyakumari District andShenkottah Taluk of Tirunelveli District)
Lingayat (Jangama)
Mahratta (Non-Brahmin) (including Namdev Mahratta)
Malayar
Male
Maniagar
Mapilla
Maravars (except Thanjavur, Nagapattinum , Tiruvarur, Pudukottai, Ramanathapuram, Sivaganga, Virudhunagar, Tirunelveli and Toothukudi Districts) Karumaravars Appanad Kondayam kottai Maravars –(except Sivaganga, Virudhunagar, Ramanathapuram, Madurai, Theni and Dindigul Districts.) Sambanad Maravars- (except Sivaganga, Virudhunagar, and Ramanathapuram Districts)
Moondrumandai Enbathunalu (84) Ur. Sozhia Vellalar
Mooppan
Muthuraja, Muthuracha, Muthiriyar, Mutharaiyar
Nadar, Shanar and Gramani ( including Christian Nadar, Christian Nadar, Christian Shanar and Christian Gramani )
Nagaram
Naikkar (in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Nangudi Vellalar
Nanjil Mudali ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Odar ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District
Odiya
Oottruvalanattu Vellalar
O.P.S. Vellalar
Ovachar
Paiyur Kotta Vellalar
Pamulu
Panar ( except in Kanniyakumari District and Shencottah Taluk of Tirunelveli District where the community is a Scheduled Caste )
Panisaivan ( including Virakodi Vellala )
**(Included in the List of OBC as per Central Govt. instruction Lr.No: 5783/BC1/95/3 Dt: 17.06.96.
Kathikarar in Kanniyakumari District
Pannirandam Chettiar or Uthama Chettiar
Parkavakulam ( including Surithimar, Nathamar, Malayamar, Moopanar and Nainar )
Perike ( including Perike Balija )
Perumkollar ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Podikara Vellalar
Pooluva Gounder
Poraya
Pulavar ( in Coimbatore and Erode Districts )
Pulluvar or Pooluva
Pusala
Reddy ( Ganjam )
Sadhu Chetty ( including Telugu Chetty, Twenty four Manai Telugu Chetty)
Sakkaravar or Kavathi ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Salivagana
Saliyar, Padmasaliyar, Pattusaliyar, Pattariyar, and Adhaviyar
Savalakkarar
Senaithalaivar, Senaikudiyar and Illaivaniar
Sheik
Sourashtra ( Patnulkarar )
Sozhiavellalar ( including Sozha Vellalar, Vetrilaikarar, Kodikalkarar and Keeraikarar )
Srisayar
Sundaram Chetty
Syed
Thogatta Veerakshatriya
Tholkollar ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Tholuva Naicker and Vetalakara Naicker
Thoraiyar
Thoriyar
Ukkirakula Kshatriya Naicker
Uppara, Uppillia and Sagara
Urali Gounder ( except Tiruchirapalli, Karur , Perambalur and Pudukottai District) and Orudaya Gounder or Oorudaya Gounder ( in Madurai ,Theni, Dindigul, Coimbatore, Erode, Tiruchirapalli, Karur , Perambalur, Pudukottai, Salem and Namakkal Districts )
Urikkara Nayakkar
Vallambar
Valmiki
Vaniyar, Vania Chettiar ( including Gandla, Ganika, Telikula and Chekkalar)
Veduvar and Vedar ( except in Kanniyakumari District and Shencottah Taluk of Tirunelveli District where the community is a Scheduled Castes)
Veerasaiva ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Velar
Vellan Chettiar
Veluthodathu Nair ( in Kanniyakumari District and Shencottah Taluk of Tirunelveli District )
Vokkaligar ( including Vakkaligar, Okkaligar, Kappiliyar, Kappiliya, Okkaliga Gowda, Okkaliya- Gowda, Okkaliya- Gowder, Okkaliya Gowda )
Wynad Chetty ( The Nilgiris District )
Yadhava ( including Idaiyar, Telugu Speaking Idaiyar known as Vaduga Ayar or Vaduga Idaiyar or Golla and Asthanthra Golla )
Yavana
Yerukula
Converts to Chritianity from any Hindu Backward Classes Community or Most Backward Classes Community or Denotified Communities except the Converts to Christianity from Meenavar, Parvatharajakulam, Pattanavar, Sembadavar, Mukkuvar or Mukayar and Paravar
Orphans and destitute children who have lost their parents before reaching the age of ten and are destitutes; and who have nobody else to take care of them either by law or custom; and also who are admitted into any of the schools or orphanages run by the Government or recognized by the Government.
2. MOST BACKWARD CLASSES
Ambalakarar
Andipandaram
Bestha, Siviar
Bhatraju ( other than Kshatriya Raju )
Boyar, Oddar
Dasari
Dommara
Eravallar ( except in Kanniyakumari District and Shencottah Taluk of Tirunelveli District where the community is a Scheduled Tribe )
Isaivellalar
Jambuvanodai
Jangam
Jogi
Kongu Chettiar ( in Coimbatore and Erode Districts only)
Koracha
Kulala (including Kuyavar and Kumbarar )
Kunnuvar Mannadi
Kurumba
Kuruhini Chetty
Maruthuvar, Navithar, Mangala, Velakattalavar, Velakatalanair and Pronopakari
Mond Golla
Moundadan Chetty
Mahendra, Medara
Mutlakampatti
Narikoravar
Nokkar
Vanniakula Kshatriya ( including Vanniyar, Vanniya, Vannia Gounder, Gounder or Kander, Padayachi, Palli and Agnikula Kshatriya )
Paravar ( except in Kanniyakumari District and Shencottah Taluk of Tirunelveli District where the Community is Scheduled Caste ) ( including converts to Christianity)
Meenavar ( Parvatharajakulam, Pattanavar, Sembadavar) ( including converts to Christianity )
Mukkuvar or Mukayar ( including converts to Christianity
Punnan Vettuva Gounder
Pannayar ( other than Kathikarar in Kanniyakumari District )
Sathatha Srivaishnava ( including Sathani, Chattadi and Chattada Srivaishnava )
Sozhia Chetty
Telugupatty Chetty
Thottia Naicker ( including Rajakambalam, Gollavar, Sillavar, Thockalavar and Thozhuva Naicker )
Thondaman
Valaiyar ( including Chettinad Valayars )
Vannar ( Salavai Thozhilalar ) ( including Agasa, Madivala, Ekali, Rajakula, Veluthadar and Rajaka) (except in Kanniyakumari District and Shencottah Taluk of Tirunelveli District where the community is a Scheduled Caste )
Vettaikarar
Vettuva Gounder
Yogeeswarar
3. DENOTIFIED COMMUNITIES
Attur Kilnad Koravars ( Salem,Namakkal, Cuddalore, Villupuram, Ramanathapuram, Sivaganga and Virudhunagar Districts )
Attur Melnad Koravars ( Salem and Namakkal District )
Appanad Kondayam kottai Maravar ( Sivaganga, Virudhunagar, Ramanathapuram, Madurai,Theni and Dindigul Districts )
Ambalakarar ( Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Ambalakkarar ( Suriyanur, Tiruchirapalli District)
Boyas ( Tiruchirapalli, Karur, Perambalur, Pudukottai, The Nilgiris, Salem Namakkal and Dharmapuri Districts)
Battu Turkas
C.K. Koravars ( Cuddalore and Villupuram Districts )
Chakkala ( Sivaganga, Virudhunagar, Ramanathapuram, Thanjavur, Nagapattinam,Tiruvarur, Pudukottai Tiruchirapalli, Karur, Perambalur, Madurai , Theni, Dindigul and the Nilgiris Districts )
Changyampudi Koravars ( Vellore and Tiruvannamalai Districts )
Chettinad Valayars ( Sivaganga, Virudhunagar and Ramanathapuram Districts )
Dombs ( Pudukottai,Tiruchirapalli, Karur and Perambalur Districts )
Dobba Koravars ( Salem and Namakkal Districts )
Dommars ( Thanjavur, Nagapattinam,Tiruvarur, Pudukottai, Vellore and Tiruvannamalai Districts )
Donga Boya
Donga Ur.Korachas
Devagudi Talayaris
Dobbai Korachas ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Dabi Koravars ( Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli, Karur, Perambalur, Pudukottai, Vellore and Tiruvannamalai Districts)
Donga Dasaris ( Kancheepuram, Tiruvallur, Tiruchirapalli, Karur, Perambalur, Pudukottai, Chennai, Salem and Namakkal Districts )
Gorrela Dodda Boya
Gudu Dasaris
Gandarvakottai Koravars ( Thanjavur, Nagapattinam,Tiruvarur, Tiruchirapalli, Karur,Perambalur, Pudukottai Cuddalore and Villupuram Districts )
Gandarvakottai Kallars (Thanjavur, Nagapattinam,Tiruvarur and Pudukottai Districts )
Inji Korvars ( Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Jogis ( Kancheepuram,Tiruvallur, Chennai, Cuddalore, Villupuram, Vellore and Tiruvannamalai Districts )
Jambavanodai
Kaladis ( Sivaganga, Virudhunagar, Ramanathapuram, Madurai,Theni, Dindigul, Thanjavur, Nagapattinam,Tiruvarur, Pudukottai,Tiruchirapalli, Karur and Perambalur Districts )
Kal Oddars ( Kancheepuram, Tiruvallur, Ramanathapuram, Sivaganga, Virudhunagar, Madurai, Theni, Dindigul,Pudukottai, Thanjavur, Nagapattinam,Tiruvarur, Tiruchirapalli, Karur,Perambalur, Tirunelveli, Toothukudi, Salem and Namakkal Districts)
Koravars ( Kancheepuram , Tiruvallur, Ramanathapuram, Sivaganga, Virudhunagar, Pudukottai,Thanjavur, Nagapattinam, Thiravarur, Tiruchirapalli, Karur, Perambalur, Tirunelveli, Thoothukadi, Chennai,Madurai, Theni, Dindigul and The Nilgiris Districts )
Kalinji Dabikoravars ( Thanjavur, Nagapattinam, Tiruvarur and Pudukottai Districts )
Kootappal Kallars ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Kala Koravars ( Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli, Karur Perambalur and Pudukottai Districts )
Kalavathila Boyas
Kepmaris ( Kancheepuram,Tiruvallur, Pudukottai, Tiruchirapalli, Karur and Perambalur Districts )
Maravars ( Thanjavur, Nagapattinam, Tiruvarur, Pudukottai, Ramanathapuram, Sivaganga, Virudhunagar, Tirunelveli and Toothukudi Districts )
Monda Koravars
Monda Golla ( Salem and Namakkal Districts )
Mutlakampatti ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Nokkars ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Nellorepet Oddars ( Vellore and Tiruvannamalai Districts)
Oddars ( Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli,Karur, Perambalur, Pudukottai, Madurai, Theni and Dindigul Districts )
Pedda Boyas ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Ponnai Koravars ( Vellore and Tiruvannamalai Districts )
Piramalai Kallars ( Sivaganga, Virudhunagar, Ramanathapuram, Madurai, Theni, Dindigul, Pudukottai, Thanjavur, Nagapattinam and Tiruvarur Districts )
Peria Suriyur Kallars ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Padayachi ( Vellayan Kuppam in Cuddalore District and Tennore in Tiruchirapalli District )
Punnan Vettuva Gounder ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Servai ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts )
Salem Melnad Koravars (Madurai, Theni, Dindigul, Coimbatore, Erode, Pudukottai, Tiruchirapalli, Karur, Perambalur, Salem, Namakkal, Vellore and Tiruvannamalai Districts)
Salem Uppu Koravars (Salem and Namakkal Districts)
Sakkaraithamadai Koravars (Vellore and Tiruvannamalai Districts)
Saranga Palli Koravars
Sooramari Oddars (Salem and Namakkal Districts)
Sembanad Maravars (Sivaganga, Virudunagar and Ramanathapuram Districts)
Thalli Koravars(Salem and Namakkal Districts)
Telungapattti Chettis (Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Thottia Naickers (Sivaganga , Virudunagar, Ramanathapuram, Kancheepuram,Tiruvallur, Thanjavur, Nagapattinam, Tiruvarur, Tiruchirapalli, Karur, Perambalur, Pudukottai. Tirunelveli, Thoothukudi, Salem, Namakkal,Vellore, Tiruvannamalai, Coimbatore and Erode Districts)
Thogamalai Koravars orKepmaris (Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Uppukoravars or Settipalli Koravars (Thanjavur, Nagapattinam , Tiruvarur, Pudukottai, Madurai, Theni, Dindigul, Vellore and Tiruvannamalai Districts)
Urali Gounders (Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Wayalpad or Nawalpeta Korachas
Vaduvarpatti Koravars (Madurai, Theni, Dindigul, Ramanathapuram, Sivaganga, Virudunagar, Tirunelveli, Thoothukudi, Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Valayars (Madurai, Theni, Dindigul, Tiruchirapalli, Karur, Perambalur, Pudukottai,Erode and Coimbatore Districts)
Vettaikarar (Thanjavur, Nagapattinam, Tiruvarur and Pudukottai Districts)
Vetta Koravars (Salem and Namakkal Districts)
Varaganeri Koravars ( Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
Vettuva Gounder (Tiruchirapalli, Karur, Perambalur and Pudukottai Districts)
List of notified Scheduled Castes
1 Adi Andhra
2 Adi Dravida
3 Adi Karnataka
4 Ajila
5 Arunthathiyar
6 Ayyanavar (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
7 Baira
8 Bakuda
9 Bandi
10 Bellara
11 Bharatar (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
12 Chakkiliyan
13 Chalavadi
14 Chamar, Muchi
15 Chandala
16 Cheruman
17 Devendrakulathan
18 Dom, Dombara, Paidi, Pano
19 Domban
20 Godagali
21 Godda
22 Gosangi
23 Holeya
24 Jaggali
25 Jambuvulu
26 Kadaiyan
27 Kakkalan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
28 Kalladi
29 Kanakkan, Padanna (in the Nilgiris district)b
30 Karimpalan
31 Kavara (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
32 Koliyan
33 Koosa
34 Kootan, Koodan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
35 Kudumban
36 Kuravan, Sidhanar
37 Madari
38 Madiga
39 Maila
40 Mala
41 Mannan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
42 Mavilan
43 Moger
44 Mundala
45 Nalakeyava
46 Nayadi
47 Padannan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)a
48 Pagadai
49 Pallan
50 Palluvan
51 Pambada
52 Panan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)a
53 Panchama
54 Pannadi
55 Panniandi
56 Paraiyan, Parayan, Sambavar
57 Paravan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
58 Pathiyan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)a
59 Pulayan, Cheramar
60 Puthirai Vannan
61 Raneyar
62 Samagara
63 Samban
64 Sapari
65 Semman
66 Thandan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)
67 Thoti
68 Tiruvalluvar
69 Vallon
70 Valluvan
71 Vannan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)a
72 Vathiriyan
73 Velan
74 Vetan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)a
75 Vettiyan
76 Vettuvan (in Kanyakumari district and Shenkottah taluk of Tirunelveli district)a
The entry is to be read as “in Kanniyakumari district and Shencottah taluk of Tirunelveli district".
Pondicherry
1 Adi Andhra
2 Adi Dravida
3 Chakkiliyan
4 Jambuvulu
5 Kuravan
6 Madiga
7 Mala, Mala Masti
8 Paky
9 Pallan
10 Parayan, Sambavar
Samban
Thoti
13 Valluvan
14 Vetan
15 Vettiyan