1. He is best known for portraying Petyr “Littlefinger” Baelish in the HBO series Game of Thrones, Tommy Carcetti in the HBO series The Wire, CIA operative Bill Wilson in The Dark Knight Rises, Stuart Alan Jones in the Channel 4 series Queer as Folk, and John Boy in the RTÉ Television series Love/Hate.
2. Gillen played Stuart Alan Jones in the groundbreaking Channel 4 television series Queer as Folk and its sequel, for which he received a British Academy Television Award nomination for Best Actor.
3. In 2004, having been spotted by producers in The Caretaker, Gillen was cast as Tommy Carcetti in the acclaimed HBO series The Wire, for which he received an Irish Film & Television Award for Best Actor in a Lead Role in Television.
4. In 2008, he was named an “Irish cult hero” by the Sunday Tribune.
5. He appeared in the 2009 film 12 Rounds, and in July of that year, he appeared in the one-off BBC2 drama Freefall.
6. 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 starred as cop killer Barry Weiss in the British crime-thriller Blitz and in the British horror film Wake Wood.
7. He 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.
8. Gillen also starred as Janson in the second film, Navulkanizování Zkoušky, in the Maze Runner trilogy.