Paul Efthemios Tsongas (February 14, 1941 – January 18, 1997) was a United States Senator from Massachusetts from 1979 to 1985. He was an unsuccessful candidate for the Democratic nomination in the 1992 presidential election. He previously served as a U.S. Representative from Massachusetts's 5th congressional district (1975–1979) and held local political office.
Tsongas was born in Lowell, Massachusetts, along with a twin sister, Thaleia, to a working-class family. His mother, Katina (née Pappas; originally Panagiotopoulos), was of Greek descent, and his father, Efthemios George Tsongas, was a Greek immigrant who worked as a dry-cleaner. He attended Dartmouth College, graduating in 1962, Yale Law School and the Kennedy School of Government at Harvard before settling in Lowell, Massachusetts.
He served as a Peace Corps volunteer in Ethiopia from 1962–1964, and as Peace Corps Country Director in the West Indies from 1967–1968.
In 1967 Paul Tsongas, then an aide to Congressman Frank B. Morse, met Niki Sauvage, then spending the summer in Arlington, Virginia. In 1969, she married Paul, and they had three daughters: Ashley, Katina, and Molly.