Fun-loving movie star and Dancer who gained fame for his role as Gene Kelly's friend Cosmo Brown in the classic 1952 film Singin' in the Rain.
He began appearing in movies at age 12, debuting in Sing, You Sinners.
He appeared as Harlow Safford in a 1996 episode of the TV series Frasier.
He and his older sister Arlene were involved in a car accident. Donald survived, but his sister did not.
He starred with Sandra Dee in the 1965 romantic comedy That Funny Feeling.