Melvyn I. Cronin (June 13, 1898 – May 9, 1977) was a United States politician. Cronin was born in San Francisco in 1898 and worked in the city's Park and Recreation Department where as a youth he taught baseball to his cousin Joe Cronin of later Boston Red Sox fame. He graduated from St. Ignatius College, later the University of San Francisco, with a degree in law and started a partnership with controversial lawyer Vincent Hallinan. During World War I he served in the United States Army. He was later a member of the California State Assembly for the 27th and 25th district, but resigned from the California State Assembly on January 4, 1942. From 1953 to 1977, he was a Judge of the California Superior Court, and served in San Francisco as Judge of the Juvenile Court under the Superior Court