Sukumar Sen (2 January 1898 – 13 May 1963) was an Indian civil servant who was the 1st Chief Election Commissioner of India, serving from 21 March 1950 to 19 December 1958. Under his leadership, the Election Commission successfully administered and oversaw independent India's first two general elections, in 1951–52 and in 1957. He also served as first Chief Election Commissioner in Sudan in 1953.

Sen was born on 2 January 1899 in a Bengali Baidya-Brahmin family. He was the elder or eldest son of a civil servant Akshoy Kumar Sen. He was educated at Presidency College, Kolkata and at the University of London. He was awarded a gold medal in Mathematics at the latter. In 1921, Sen joined the Indian Civil Service, and served in various districts as an ICS officer and as a judge. In 1947, he was appointed Chief Secretary of West Bengal, the senior-most rank that an ICS officer could attain in any state in British India. He was still serving in that capacity when he was sent on deputation as chief election commissioner in 1950. He was among the first recipients of the civilian honour of Padma Bhushan. He married Gouri and had two sons and daughters each with her.

Sen was the elder brother of Ashoke Kumar Sen (1913–1996), Union Law Minister and a noted Indian barrister. Another brother was Amiya Kumar Sen, an eminent doctor, who was the last man to see Rabindranath Tagore alive. It is said that Amiya Sen preserved Tagore's last poem, which he had written down at the poet's dictation, and later donated it to Indian Museum in Kolkata.

Sukumar Sen, in his role as the Chief Election Commissioner of India, was charged with overseeing the 1952 Indian General Election, which was the first election in the history of independent India.

Historian Ramachandra Guha wrote of Sukumar Sen in The Hindu in 2002, on the 50th anniversary of independent India's first general election:

Nehru's haste [in wanting India's first general election] was understandable, but it was viewed with some alarm by the man who had to make the election possible, a man who is an unsung hero of Indian democracy. It is a pity we know so little about Sukumar Sen. He left no memoirs and, it appears, no papers either. ...

It was perhaps the mathematician in Sen, which made him ask the prime minister to wait. No officer of State, certainly no Indian official, has ever had such a stupendous task placed in front of him. Consider, first of all, the size of the electorate: 176 million Indians aged 21 or more, of whom about 85 per cent could not read or write. Each voter had to be identified, named and registered. This registration of voters was merely the first step. For how did one design party symbols, ballot papers and ballot boxes for a mostly unlettered electorate? Then, polling stations had to be built and properly spaced out, and honest and efficient polling officers recruited. Voting has to be as transparent as possible, to allow for the fair play of the multiplicity of parties that would contest. Moreover, with the general election would take place elections to the State Assemblies. Working with Sukumar Sen in this regard were the election commissioners of the different provinces, also I.C.S. men.

Tinker and Walker write that Sukumar Sen was aided by two Regional Election Commissioners plus one Chief Election Officer for each state.