A criminal was someone who committed a crime.
There were several Foamasi criminal organisations, including the West Lodge, Dark Peaks Lodge, South Lodge and Twin Suns Lodge. (TV: The Leisure Hive, PROSE: Placebo Effect)
The Elective was a criminal syndicate within the Union, based on Hexdane. (PROSE: The Crystal Bucephalus)
Kane and Xana were part of a criminal gang on Proamon. When they were going to be arrested, Xana killed herself rather than face a trial. Kane was exiled to Svartos for his punishment. (TV: Dragonfire)
The word "crook" was a slang term for criminal. US President Richard Nixon famously declared that he was "not a crook" during the Watergate scandal. (PROSE: Tricky Dicky [+]Loading...["Tricky Dicky (short story)"])
Before becoming the Tenth Doctor's companion, Majenta Pryce had been a member of a criminal group called the Crimson Hand. (COMIC: The Crimson Hand)
Dirk Slipstream was a criminal who served time in Volag-Noc after being caught by the Doctor. (PROSE: Night of the Humans)
Beep the Meep was the leader of the Meeps and a galactic criminal who referred to himself as the Most-High. (COMIC: Doctor Who and the Star Beast)
Kerko was a Blowfish criminal who came to 21st century Cardiff via the Cardiff Rift. (PROSE: The Undertaker's Gift)
Prior to coming into the employ of River Song, Nardole had been a criminal, a period of his life he sought to make amends for. (TV: Oxygen, The Doctor Falls)
By Time Lord law, Renegade Time Lords were considered criminals. (PROSE: A Brief History of Time Lords)
In the Unbound Universe, the Ke Le Divisions were composed of criminals that the Master had brainwashed with his Keller Machines. (AUDIO: Sympathy for the Devil)