In a psychic illusion the Master created for the Seventh Doctor, he showed to him the Chief clown as a janitor working at the Paradise Towers. He saw a poster of the Circus, took it off and ran away to join it.
The clown arrived to the Circus as Kingpin was holding auditions for new acts, and won the contest. The Master contacted him telepathically and made of him the new leader of the Circus, exploiting his ambition for success as "the greatest clown in the galaxy". He reprogrammed the robot bus controller built by Bellboy to kill anyone trying to leave, proposed the Circus should sell merchandise and proposed a talent contest to attract the energy of new talents to feed the Master.
When the Doctor, contacted for help by Kingpin, arrived to the Circus, the Clown reprogrammed Bellboy's kites to track him down and kill him. Just like the other artists, he was released from the Master's power when Kingpin destroyed the talisman the Master used to control them, and also lost the memory of what happened. (AUDIO: The Psychic Circus)
When the Gods of Ragnarok took possession of the Circus, the Chief Clown was ready to become their servant. He was apparently in charge of the circus' security; while in this capacity, he and the mute robot clowns lured people into the ring where they were killed for entertainment. Not wanting to lose his control over the circus, he wore undertakers' clothing and travelled in a hearse with dark-tinted windows, hunting down escapees such as Bellboy and Flowerchild.
He and a group of his robot clowns searched for Ace, Mags and Kingpin after they escaped from the circus. The clowns soon located the trio, but Ace activated a robot built by Bellboy, which, after destroying the robot clowns, killed the chief. (TV: The Greatest Show in the Galaxy)