(written from a Production point of view)
Prior to his appearance in the Roswell-themed Star Trek episode, he starred in a 1994 television movie, Roswell, in which he played an Area 51 officer.
His first motion picture appearance was in the 1987 movie Some Kind of Wonderful, with Molly Hagan. He also appeared in the thriller Blackout (1996, with Brad Dourif, Marta Dubois, Jeremy Roberts, Lance LeGault, Tom Poster, Brad Greenquist, Chip Heller, and Azalea Davila), the thriller Volcano (1997, with Jacqueline Kim), and the action thriller Broken Arrow (1997, with Christian Slater, Casey Biggs, Bob Gunton, Vyto Ruginis, Kurtwood Smith, and Raymond Cruz). In 2002, he starred in Phone Booth, which also featured Josh Pais. MacDonald has also guest-starred in True Detective and Agents of S.H.I.E.L.D.
He played the recurring character Detective Stein in Buffy the Vampire Slayer (with his "Little Green Men" co-star Armin Shimerman).