There's a slew of 'em, and probably not a complete list:
"Brando married actress Anna Kashfi in 1957. Kashfi was born in Calcutta and moved to Wales from India in 1947. Brando and Kashfi had a son, Christian Brando, on May 11, 1958; they divorced in 1959.
In 1960, Brando married Movita Castaneda, a Mexican-American actress seven years his senior; they were divorced in 1962. They had two children together: Miko Castaneda Brando (born 1961) and Rebecca Brando (born 1966).
Tahitian actress Tarita Teriipia, who played his love interest in Mutiny on the Bounty, became Brando's third wife on August 10, 1962. She was 20 years old, 18 years younger than Brando... Teriipia became the mother of two of his children: Simon Teihotu Brando (born 1963) and Tarita Cheyenne Brando. Brando also adopted Teriipia's daughters, Maimiti Brando (born 1977) and Raiatua Brando (born 1982). Brando and Teriipia divorced in July 1972.
Brando had a long-term relationship with his housekeeper Maria Christina Ruiz, by whom he had three children: Ninna Priscilla Brando (born May 13, 1989), Myles Jonathan Brando (born January 16, 1992), and Timothy Gahan Brando (born January 6, 1994). He had four more children by unidentified women: Stephen Blackehart (born 1967); Michael Gilman (born 1967), who was adopted by Brando's longtime friend Sam Gilman; Dylan Brando (born 1968), and Angelique Brando. Brando also adopted Petra Brando-Corval (born 1972), the daughter of his assistant Caroline Barrett and novelist James Clavell"