Adric, played by Matthew Waterhouse.
Adric (Matthew Waterhouse) taken during his time in Dr Who.
Matthew Waterhouse, taken in 1993.
Adric was an Alzarian from E-Space, and ended up joining the Doctor and Romana on their travels, eventually leaving E-Space and journeying to N(normal)-Space. Adric was later killed by the Cybermen as he was trapped in a craft that was to wipe out the dinosaurs on Earth. Adric was an exceptionally bright mathematician, unusally so for someone his age. He was quick to pick things up, such as learning to fly the TARDIS, and could even crack Cyber-code. Adric's mathematical knowledge was even harnessed by the Master to create the city of Castrovalva, which was based on Space-Time distortion. Adric was also extremly arrogant and had no time for the 5th Doctor, with both having a somewhat thorny relationship that was resolved just before Adric's death in Earthshock.
On a personal note, I detest Adric. He is obnoxious and downright irritiating and he is, in my view, the worst companion Dr Who has ever had. Still, at least they had the guts to kill him in Earthshock- I actually quite enjoyed that moment!
Adric appeared in: Full Circle, State of Decay, Warrior's Gate, The Keeper of Traken, Logopolis, Castrovalva, Four to Doomsday, Kinda, The Visitation, Black Orchid, Earthshock.
Despite viewing numerous sites on the Dr Who companions, I cannot find any information on Matthew Waterhouse, other than he was 20 when he left the show.