Aggrotron!

 (subtitled The Sci-Fi Comic for Far Out Kidz) was a comic book edited by Grakk. It featured characters which included Big Bustard, Captain Cannibal, D.A.C.H.S.Haund 1, the Trembling Hand, the Mangler, and its most popular character, Courtmaster Cruel.

Izzy Sinclair enjoyed Aggrotron, which was sold in her native Stockbridge by Grubb and Sons, where she had a standing order for each issue. The 56th and final issue, published on 8 April 1988, eluded her as a child, and was so rare as to be essentially lost. She especially desired it as it would have revealed the identity of Courtmaster Cruel.

As a young adult, when given the opportunity by the Eighth Doctor to travel anywhere in time and space, she chose to return to Grubb and Sons on the day the 56th issue was published so she could finally read it. She again almost bought it, but it was destroyed by Suits — characters from the comic — before she could take possession of it. Investigating, the Doctor and Izzy discovered that the magazine was published by extraterrestrials who had based the characters on themselves. They learned that Derek O'Dell, a native of the 51st century who had taken the identity of Courtmaster Cruel to deal with lawlessness in his present, found the original artwork for issue 56. When he discovered the identity of Courtmaster Cruel, he was mortified. Since the Courtmaster was in fact a girl, he believed it would ruin his authority to deal with criminals, so he came back in time to destroy all copies of the comic. Though the Doctor couldn't understand how this was a problem, Izzy readily agreed with Derek. (AUDIO: Izzy's Story)

Behind the scenes

 * The comic Aggrotron is a combination of two comics edited by Pat Mills - and, with Courtmaster Cruel (in name, at least) a parody of 2000AD character.
 * The spelling of Kidz is actually specified by the Doctor.