He had a particular interest in experimenting with a transmogrifier, which mutated its victims according to their own unconscious wishes. He had mutilated his own face by experimenting with it and wore a mask which covered one eye.
Quillam subjected Peri Brown and Areta to the transmogrifier, which began mutating them into a bird and a reptile, respectively, but the Sixth Doctor rescued them. He and the Chief Officer were later killed by deadly vines in the Punishment Dome. (TV: Vengeance on Varos)