Pattom A. Thanu Pillai (15 July 1885 – 27 July 1970) was an Indian politician and freedom fighter who served as the 2nd Chief Minister of Kerala from 1960 to 1962. He was considered as a central figure in Kerala politics.

Born in Thiruvananthapuram, A.Thanu Pillai was the son of Varadayyan and Eswari Amma.^[1] While working as Deputy Chief in the State Agriculture department, he earned his law degree from Law College, Thiruvananthapuram and started his legal practice as an advocate. Under the influence of his mentor A. Narayana Pillai, he was attracted towards the newly formed Travancore State Congress and he abandoned full-time practice in favour of agitating for responsible government.^[1] Following the Narayana Pillai sedition trial, he took over the leadership of Indian National Congress in Travancore.

First Ministry of the state of Travancore-Cochin headed by Parur T. K. Narayana Pillai resigned on 24 February 1951 following a corruption charge on the ministry. He was succeeded by C. Kesavan as the second Chief Minister of Travancore-Cochin. The first assembly of the state of Travancore-Cochin was dissolved on 12 March 1952 following the resignation of C Kesavan. Following the elections to the Legislative Assembly, held on 27 March 1952, A. J. John became the third Chief Minister of Travancore-Cochin. The second assembly of Travancore-Cochin lasted till 16 March 1954. By that time Thanu Pillai left Indian National Congress and joined Praja Socialist Party (PSP). In the election for the third Legislative Assembly of Travancore-Cochin held in 1954, Praja Socialist Party won 19 seats (out of the contested 38) and formed a coalition government along with the Indian National Congress (INC) who had won 45 seats. Thanu Pillai became the fourth Chief Minister of Travancore-Cochin with the support of INC on 16 March 1954. He resigned on 10 February 1955 and was succeeded by Panampilly Govinda Menon as the last Chief Minister of Travancore-Cochin. He remained in office till 23 March 1956. After that, the state remained under President's rule till 5 April 1957. During this time the State of Kerala was formed under the States Reorganisation Act, 1956.

After the first ever elections to the Kerala Legislative Assembly in 1957, the Communist Party of India emerged as the single largest party. E M S Namboodiripad formed the first elected government with the support of 5 independent legislators. The government was not able to complete its full 5 year term. The Communist-led government was dissolved as a consequence of the movement known as the Vimochana Samaram (Liberation Struggle). The Communist government was dismissed on 31 July 1959 and President's rule was imposed in the state under Article 356 of the constitution. Fresh elections were held in 1960 and Thanu Pillai became the second Chief Minister of Kerala, as head of a PSP-INC-Muslim League coalition administration.^[1] He assumed office on 22 February 1960. However, he resigned on 26 September 1962 to make way for R. Sankar of the INC as the next Chief Minister of the state. He was appointed Governor of Punjab on 1 October 1962 and later Governor of Andhra Pradesh on 4 May 1964 and remained in office till 11 April 1968.^[1]

Two years after resigning as Governor of Andhra Pradesh, Pattom Thanu Pillai died on 27 July 1970, aged 85 at his home in Thiruvananthapuram. He was cremated with full state honours at the premises of his home.