Sergiu Cunescu (March 16, 1923—March 16, 2005) was a Romanian social democratic politician, the leader of the Social Democratic Party of Romania (PSDR) between 1990 and 2001.
Born in Bucharest, he graduated from the Electromagnetics branch of the Polytechnic Institute. Although his father was a prominent PSDR member, Sergiu Cunescu was initially sympathetic of the National Peasants' Party, and led the latter party's Polytechnic group for a period. For a while after 1948, he was a political prisoner in Communist Romania, before being allowed to return to his engineering career.
In January 1990, soon after the 1989 Romanian Revolution, Cunescu was instrumental in the recreation of the PSDR as an independent group (it had been absorbed into the Romanian Communist Party through an abusive maneuver, in November 1947). He was elected to the Chamber of Deputies of Romania in 1990, 1992 and 1996, and was a member of the Joint Romania-European Union Parliamentary Committee, and later of the Chamber's External Policies and European Integration Committee - under the PSDR-backed Romanian Democratic Convention governments.
He retreated from public life after the union of the PSDR with the Romanian Party of Social Democracy, which he had voted against.