Ianto Jones is a fictional character in the BBC television programme Torchwood, a spin-off from the long-running series Doctor Who, played by Welsh actor Gareth David-Lloyd. A regular within the show, Ianto appears in every episode of the programme's first three series excluding the finale of series 3, as well as two crossover episodes of Torchwood's parent show, Doctor Who. Additionally, Ianto appears in Expanded Universe material such as the Torchwood novels and audiobooks, comic books and radio plays. Within the narrative of the series, Ianto begins as general support officer for Torchwood Three, a team of alien hunters stationed in Cardiff, and develops into an active field agent. Initially the regular character with the least screen time, Ianto's role expanded in response to growing cult appeal.

Torchwood is a British science fiction television programme created by Russell T Davies. A spin-off of the 2005 revival of Doctor Who, it aired from 2006 to 2011. The show shifted its broadcast channel each series to reflect its growing audience, moving from BBC Three to BBC Two to BBC One, and acquiring American financing in its fourth series when it became a co-production of BBC One and Starz. Torchwood is aimed at adults and older teenagers, in contrast to Doctor Who's target audience of both adults and children. As well as science fiction, the show explores a number of themes, including existentialism, LGBTQ+ sexuality, and human corruptibility.