Gareth David-Lloyd was born in Bettws, Newport. His first acting role was as a robot in a junior school play. As a teenager, Gareth joined the Gwent Young People's Theatre in Abergavenny, appearing in several plays including Macbeth and Henry V, in which he played the title roles. When former Labour Party leader Neil Kinnock saw the young Gareth performing at Monmouth Castle, he sent him 250 pounds to use towards his acting career.
Whilst studying at Coleg Gwent, Crosskeys, he appeared in various local stage productions at the Dolman Theatre in Newport and the Sherman Theatre in Cardiff. He went on to train at the National Youth Theatre, before moving to Reading to pursue his acting career with The Rep College. His roles have included Macheath in The Threepenny Opera, Sebastian in Twelfth Night on stage and his early appearances in television programmes such as Absolute Power, Casualty, Rosemary & Thyme and The Bill.
Gareth returned to Wales in 2006 for the filming of his first regular television role, Ianto Jones in Torchwood, appearing in 30 episodes out of 31 in series 1 - 3, plus two episodes of Doctor Who. This role led to him being dubbed a science fiction cult hero by SFX magazine. He has since worked with James Moran (Torchwood and Doctor Who writer) on the innovative web drama Girl Number 9, had further TV guest roles in The Bill, Caerdydd and Warehouse 13, and movies Sherlock Holmes (as Watson) and Red Faction: Origins (as Adam Hale).
Outside of screen and stage work, Gareth has undertaken recordings of a number of MR James and HP Lovecraft short stories, as well as a Torchwood audiobook and seven radio plays, plus a short story reading on BBC Radio 4.
Gareth is also interested in writing, directing and producing, as well as performing and recording with band Blue Gillespie.