[27][additional citation(s) needed] In his own writings Karunanidhi said that his family were of the Isai Vellalar, a community who had traditionally played musical instruments at ceremonial occasions;[23][24] however his political rival M. G. Ramachandran and some observers contested that and said that he was of Telugu ancestry.

His father also asked the local headmaster to set up special tutoring courses for Karunanidhi and paid a tuition fee of milk every morning and evening.

[34] As a teenager he was captivated by the political writings of Tamil leaders including Panagal Arasar, Periyar and Pattukottai Azhagirisamy (after whom Karunanidhi later named one of his sons).

Karunanidhi joined the anti-Hindi protests sparked by the provincial government's legislation making Hindi-education mandatory in schools, and in 1938 organised a group of boys to hold demonstrations travelling around Tiruvarur on a cycle rickshaw.

The taste for activism however stuck and in the ensuing years, after a brief flirtation with Communism, Karunanidhi started following the work and speeches of leaders of Justice Party, Self-Respect Movement and Dravidar Kazhagam.

[23] According to Karunanidhi, he joined the Periyar's movement when he saw his father hurriedly rising and tied his towel to his waist from his head as a gesture of servitude when an upper caste landlord walked past him.

During the result day, unable to face his family over his third consecutive failure, he left to Thopputhurai in search of his classmate Asan Abdul Kaathar who consoled him.

Kallakudi was renamed as "Dalmiapuram" by the state administration led by Rajagopalachari to commemorate the North Indian business magnate Ram Krishan Dalmia, who owned a cement factory there.

[51] DMK wanted to change the name back to Kallakudi because Ram Krishna Dalmia depicted north Indian hegemonic power and predatory businesses.

He began sending daily letters to his party members, whom he referred to as udan pirappukal (blood brothers), a practice he followed for fifty years.

[20] Karunanidhi sponsored and presided over a State Autonomy Conference in Madras on 12 September 1970, which included Periyar, West Bengal Chief Minister Ajoy Mukherjee, numerous Parliamentarians, and other dignitaries.

[62] Karunanidhi's administration established the Sattanathan commission for backward classes in 1969 to recognise underprivileged groups and give them with representation in government employment and educational institutions.

"[73] Karunanidhi established the Government Servants' Family Benefit Fund Scheme to give financial compensation to an employee's relatives in the event that he loses his job owing to permanent complete disability, medical incapacity, or death.

[20] In February 1982, Karunanidhi embarked on a week-long padayatra from Madurai to Tiruchendur, spanning about 200 kilometres, in order to seek 'justice' for Subramania Pillai, a Hindu Religious and Charitable Endowments Department (HR & CE) officer who was found dead in November 1980.

In December 1984, contested as allies in both Lok Sabha and the State Assembly which conducted together and were carried to victory by the sympathy generated for Indira Gandhi and MGR who was undergoing a Kidney transplant in New york.

[20] Karunanidhi allowed the LTTE to use Tamil Nadu as a rear base for its battle for Eelam Between 1989 and 1991, even after Prabhakaran took up arms against the Indian Peace Keeping Force (IPKF).

[97] The Karunanidhi administration is then dismissed and placed under presidents rule by the Chandra Shekhar led union government after only two years of its five-year tenure due to its inability to act against Sri Lankan Tamil militants.

The DMK joined the BJP-led National Democratic Alliance to fight the elections, portraying Vajpayee as a softer ideological character than LK Advani.

[108] Karunanidhi devised the Uzhavar Sandhai plan in 1999, which aims to promote farmer-to-consumer communication and remove the middleman and helped farmers gain more remuneration.

[117] In the midnight 30 June 2001, he was arrested on the orders of J. Jayalalithaa as an act of Vendetta[20] based on a First Information report over of alleged losses of ₹12 crore on construction of flyovers filed by Commissioner J. C. T. Acharyalu who Karunanidhi had earlier kept under suspension.

[133] Karunanidhi launched the "Kalaignar Kapitu Thitam" in 2009 to give people from economically disadvantaged backgrounds receive quality medical treatments without discrimination.

Multiple medical camps were held around the state as part of the Varumun Kappom Thittam initiative, benefiting a huge portion of Tamil Nadu's population.

During this period he and M. G. Ramachandran, then an upcoming actor and later day founder of AIADMK party started a long friendship eventually turning into rivals in later years politics.

His stint with Jupiters Pictures then housed at Central Studios continued for another MGR starrer Abhimanyu, Marudhanaattu Ilavarasi (1950) starring M. G. Ramachandran and V. N. Janaki.

Around late 1949, T. R. Sundaram of Modern Theatres Studio in Salem engaged Karunanidhi as scriptwriter for the film Manthiri Kumari starring M. G. Ramachandran which would become be a blockbuster hit.

[157] The story contained condemnation of Tamil Nadu's severe social disparities, India's power difference between South and the North, and the moral corruption of the Hindu priestly caste.

The books written by Karunanidhi include Sanga Thamizh, Thirukkural Urai, Ponnar Sankar, Romapuri Pandian, Thenpandi Singam, Vellikizhamai, Nenjukku Needhi, Iniyavai Irubathu and Kuraloviam.

[159] Karunanidhi's stage plays[160] include: Manimagudam, Ore Ratham, Palaniappan, Thooku Medai, Kagithapoo, Naane Arivali, Vellikizhamai, Udhayasooriyan and Silappathikaram.

He married Padmavathi Ammal on 13 September 1944, under the Dravidian movement's Self-Respect form of marriage where the bride and groom exchanged garlands, without a thaali (mangalsutra), and specifically without Brahmin priests presiding.

"[193] In an April 2009 interview to NDTV, Karunanidhi made a controversial remark stating that "Prabhakaran is my good friend" and also said, "India could not forgive the LTTE for assassinating Rajiv Gandhi".