He is also well known to sci-fi fans as Ky in the Doctor Who storyline The Mutants (1972). He reappeared in Doctor Who in 2012, as Abraham in the episode "A Town Called Mercy".
Hagon's voice-over credits include the radio drama Judge Dredd: Jihad, as a psychotic clone of Toby Longworth's Joseph Dredd; the 1996 Manga Video dub of Lupin III: The Mystery of Mamo and Lupin III: Bye Bye Liberty Crisis as Goemon Ishikawa XIII; and the 2015 video game Batman: Arkham Knight, as a clone of the Joker (voiced by fellow Star Wars alumnus Mark Hamill).
- The Jedi Master's Quizbook
- "Rebel Pilot Reunion" — Star Wars Insider 32
- "Rebel Rumblings" — Star Wars Insider 60
- "Launch Pad" — Star Wars Insider 152
- "200 Reasons Why We Love Star Wars" — Star Wars Insider 200
- Star Wars: The Skywalker Saga – The Official Collector's Edition
- Star Wars Starships & Vehicles 14
- "Red Three Standing By!" — Star Wars Insider 213