In 1984, Critchlow had his debut in mainstream comic books when he contributed "The Black Currant" strip for "Warrior" issue 26. In the 1990s, after the Thrud strip had concluded in "White Dwarf", Critchlow began working with 2000AD, and he contributed artwork for Pat Mills' "Nemesis & Deadlock" strip. Critchlow contributed art for numerous strips in 2000AD, including "Tharg's Future Shocks", "Judge Dredd", "Mean Machine: Son of Mean Machine", "Tales of Telguuth", "Flesh", and full colour work for the 1995 crossover "Judge Dredd/Batman:The Ultimate Riddle".