
In 2000 Myles took on the central role of Ceri Owen (Née Lewis) in the
BBC Wales drama
Belonging. Her longest role to date, Myles played Ceri from the series' first episode through to its final series in 2008; returning for a one off special in 2009. In 2001, Myles undertook a role in the television film
Score and the TV mini-series
Tales from Pleasure Beach. From 2003, Myles based herself in
Stratford upon Avon, initially playing
Lavinia in the
Royal Shakespeare Company production of
Titus Andronicus, for which she received the Sunday Times Ian Charleson award in 2004. She has also played Bianca in
The Taming of The Shrew and in 2005, appeared opposite
Michael Gambon in
Henry IV, Part I and
II at the
National Theatre.
Myles appeared in the ITV drama
Colditz in 2005. She took a supporting role in the
Doctor Who episode "
The Unquiet Dead", playing servant girl Gwyneth. This brought her to the attention of Lead Writer
Russell T Davies, who would progress to create and produce
Torchwood. Considering her to be "one of Wales' best-kept secrets", Davies wrote the role of Gwen Cooper in
Torchwood specifically for Myles. Speaking on her casting, Myles stated that having the part written for her was like having her "own personal Oscar."
Gwen, an
audience surrogate character,
is characterised by Myles as Torchwood's "social worker", who "can run and fight and stand in her own corner and win." Her role in
Torchwood also led to Myles making a second appearance in
Doctor Who, for its Fourth series' finale, alongside
Torchwood co-stars
John Barrowman and
Gareth David-Lloyd.
Myles has appeared in every episode of
Torchwood. Myles also appeared in the premiere episode of
Merlin, called "The Dragon's Call" where she played
Lady Helen of Mora and
Mary Collins, a witch who impersonated her. Her performance in this role was described positively by
Anthony Head, who said that 'she did it dead straight and very scarily. There was one moment she was delivering a speech to me in full prosthetic make-up... The French background artists didn’t speak English but burst into applause at the end because they were moved by the emotion of it.' She portrayed the character of Maggy Plornish in
Andrew Davies' 2008 adaptation of
Little Dorrit, which later went on to win seven Emmy awards. Early 2008 also saw the actress host a radio show centred around Welsh boxer
Joe Calzaghe and narrate a short story,
Sorry for the Loss by Bridget Keehan, both airing on BBC Radio Wales. 2009 saw her star in the award winning independent Welsh film
A Bit of Tom Jones as well as the one-off Drama,
Framed, for BBC Wales, alongside Trevor Eve. In July 2010, Myles announced she would appear in an original
BBC Cymru Wales TV series,
Baker Boys, co-written by
Helen Raynor and
Gary Owen and airing in early 2011. 2011 also saw Myles provide the voice of the Dalish elf Merrill in the Bioware video game
Dragon Age 2. In July 2011, to coincide with Torchwood's fourth series Myles presented part of a
BBC Wales Documentary entitled
Wales and Hollywood, which featured the actress travelling to the
Hollywood Walk of Fame to find the Welsh talent honoured there. In 2012 Myles returned to the stage in
Zach Braff's play
All New People, ran for ten consecutive weeks at the West End's
Duke of York's Theatre following runs at the
Manchester Opera House (8–11 February 2012) and the
King's Theatre in Glasgow (14–18 February). In 2013 she took the title role in the BBC1 drama
Frankie, filmed in Bristol, which follows the life of a
district nurse who cares more about her patients than her own life.