He is famous for his roles as Captain `` Howling Mad '' Murdock on the hit 1980s action show The A-Team , and Reginald Barclay in Star Trek : The Next Generation , Star Trek : Voyager and the film Star Trek : First Contact . He is best known for his roles as Captain `` Howling Mad '' Murdock on the 1980s action show The A-Team , and as Reginald Barclay in Star Trek : The Next Generation , Star Trek : Voyager , and the film Star Trek : First Contact .