Thomas William Selleck (/ˈsɛlɪk/; born January 29, 1945) is an American actor, film producer, and California Army National Guard veteran. He is most known for starring as private investigator Thomas Magnum in the television series Magnum, P.I. (1980–1988), as Peter Mitchell in Three Men and a Baby, and as NYPD Commissioner Frank Reagan in Blue Bloods on CBS since 2010.