S. Balakrishnan, also known as So. Balakrishnan or So.Ba, was a veteran Indian politician, President of Tamil Nadu Congress Committee (TNCC) and Member of the Legislative Assembly of Tamil Nadu for 18 years. He was the Leader of the Opposition in the 11th Tamil Nadu Legislative Assembly (1996-2001).

Balakrishnan was elected to the Tamil Nadu Legislative Assembly]] as an Indian National Congress (INC) candidate from Mudukulathur constituency in the 1977 and 1991 elections and as a Tamil Maanila Congress (Moopanar) (TMC) candidate from the same constituency in 1996. He was also elected from Kadaladi as a TMC candidate in the 2001 election.

Balakrishnan unsuccessfully contested elections in the same Ramanathapuram district on other occasions. In the General Elections of 1971, he was runner-up in the Ramanathapuram Lok Sabha constituency with 139,276 votes (38.87% of the total). In the state elections of 1980, he contested from Mudukalathur and polled 37,175 votes (44.77%) but lost the election by 5536 votes. In the 1989 state elections, he contested from Kadaladi, a coastal constituency that neighboured Mudukalathur, and gained 32,273 votes, which was 409 (0.38%) less than the winner. The total number of votes that were rejected or declared invalid in that constituency during the election was 1878 (1.71%)

Mr Balakrishnan, who met with a road accident in September 2004 and sustained serious injuries in his spinal cord, died at 0400 hrs at Paramakudi, his home town after being discharged from a private hospital in Madurai last evening. He was 70. He is survived by his wife, four sons and a daughter.

The cremation will take place tomorrow at Paramakudi in Ramanathapuram district, family sources said. Battling for life for the past two years, Mr Balakrishnan, popularly known as ”So Ba”, recovered briefly last year, to fell ill again. His condition deteriorated in the last two months and became worse last evening, when he was taken home. Joining the Congress movement at an early age, Mr Balakrishnan had worked as the true disciple of late stalwart K Kamaraj and had served the party in various capacities. He was first elected to the state assembly from Mudukalathur in 1977 and relected from the constituency in 1991 and 1996. He was elected from Kadaladi, also in Ramanathapuram district for the fourth term in the 2001 assembly elections. While he was the senior leader of the now defunct Tamil Maanila Congress, he had served as leader of the oppositon when the DMK was in power during 1996-2001.