Stage Gillen's first role on a London stage was at the
Bush Theatre, in
Billy Roche's
Wexford Trilogy. Soon afterwards he had a role in
Juno and the Paycock at the
Royal National Theatre. In 2008, Gillen played Teach in the Dublin
Gate Theatre's 2007 production of
David Mamet's
American Buffalo.
Screen During the 1990s, Gillen played a number of roles in television dramas and series, including a TV adaptations of the
Wexford Trilogy. In 1997, he appeared alongside playwright
Harold Pinter in
Mojo In 2000, he starred in
The Low Down, director
Jamie Thraves' first feature film. The film was named among the "neglected masterpieces" of film history by
The Observer in its rundown of 50 Lost Movie Classics. In 2003, he played the villain in the
Shanghai Noon sequel,
Shanghai Knights. In 2011, Gillen began playing
Petyr "Littlefinger" Baelish on the HBO series
Game of Thrones, for which he received his second Irish Film & Television Award nomination. He appeared in seven seasons, until his character's death in the season 7 finale "
The Dragon and the Wolf". He starred as cop killer Barry Weiss in the British crime-thriller
Blitz and in the British horror film
Wake Wood. Gillen played
crime boss John Boy in the acclaimed Irish crime-drama
Love/Hate, for which he received his third Irish Film & Television Award nomination and second win. In 2012, he played
CIA operative Bill Wilson (the character's name is from the novelisation; his name is not directly said in the film's script) in
The Dark Knight Rises, his first role in a major Hollywood film. Gillen said he enjoyed playing the role, but preferred low-budget lead roles to blockbuster bit-parts. which references the dialogue between Wilson and
Tom Hardy's character
Bane in said scene. The same year, Gillen also starred in the British spy-drama
Shadow Dancer, and was announced as the new host of the music show
Other Voices. He starred in the
BBC five-part thriller
Mayday in 2013, and the Irish comedy-drama film
Calvary the following year. He shared a
Screen Actors Guild Award nomination with the cast of
Game of Thrones for Outstanding Performance by an Ensemble in a Drama Series. Gillen also starred in the short film
Ekki Múkk, created for the
Valtari Mystery Film Experiment by Icelandic band
Sigur Rós, as well as Janson in the second film,
The Scorch Trials, and third film,
Maze Runner: The Death Cure, in the
Maze Runner trilogy. Gillen played
Queen's manager
John Reid in the biopic
Bohemian Rhapsody, which was released on 2 November 2018. He starred as Aidan in the short film titled ''I Didn't...I Wasn't...I Amn't'', written and directed by Irish actress
Laoisa Sexton. He starred in
The History Channel's two-season series
Project Blue Book from 2019 to 2020. Gillen played Dr.
J. Allen Hynek, a brilliant and underappreciated college professor who is recruited by the U.S. Air Force to spearhead an operation named Project Blue Book. He is joined by his partner Air Force Capt. Michael Quinn as they investigate UFO sightings around the country. Gillen co-wrote the script of and starred in
Jamie Thraves' fourth feature film,
Pickups (2017). This was the third collaboration with Thraves. He plays Frank Kinsella, a member of a prominent Irish crime family, in the
RTÉ One crime drama
Kin (2021–2023). ==Personal life==