Timothy Busfield (born June 12, 1957) is an American actor and director. He has played Elliot Weston on the television series thirtysomething; Mark, Kevin Costner's brother-in-law in Field of Dreams; and Danny Concannon on the television series The West Wing. In 1991 he received a Primetime Emmy Award as best supporting actor in a drama series. He is also the founder of the 501c3 non-profit children's theatre Fantasy Theatre for Children and B Street Theatre.