Nicktoonsters was a short-lived television channel in the United Kingdom, which launched on 18 August 2008 on Sky. It was a spinoff channel of Nicktoons. Its license first appeared on the OFCOM website in September 2007 (initially named "Nicktoons 2", this was changed to Nicktoonsters on 3 July 2008). The network was targeted to 5-8 year old children and aired mainly older library content from Nicktoons, broadcasting twelve hours per day from 7:00 a.m. to 7:00 p.m. daily, with Comedy Central Extra +1, a one-hour timeshift service of Comedy Central Extra taking the other twelve hours in a channel-sharing arrangement upon the launch of Nicktoonsters (CCE+1 had previously been a 24-hour feed).
The channel launched with a Rugrats marathon week before it commenced its regular schedule on 25 August 2008, at first exclusively formed of "classic" shows. In later months, newer programmes such as Fairly Odd Parents and SpongeBob SquarePants aired on holidays and weekends.
The channel ended its run on 31 July 2009 at 7:00 p.m, nearly a year after its launch. A +1 feed of Nicktoons known as Nicktoons Replay replaced it the next day on 1 August 2009. Comedy Central Extra eventually reclaimed the full 24 hours of channel space on 2 October 2012 when Nicktoons Replay was discontinued.