Can’t Place Ser Duncan? Here’s Where You’ve Seen A Knight of the Seven Kingdoms Star Before
Game of Thrones is about to mint its next breakout: Peter Claffey. Set to arrive in A Knight of the Seven Kingdoms next year, the rising actor has quietly built a résumé on stage and screen — which is why he might already look familiar.
Not ringing a bell when you hear the name Peter Claffey? Give it a minute. HBO is handing him the keys to A Knight of the Seven Kingdoms, where he plays the legendary hedge knight Ser Duncan the Tall. It is his first big lead, and yeah, Dunk is canonically pushing seven feet, so the casting vibe checks. If you feel like you have seen Claffey somewhere before, you probably have — he has been quietly stacking stage and screen credits after starting his adult life smashing into people for a living as a rugby union pro with Irish clubs Ballinasloe, Galwegians, and Terenure College.
Where you have actually seen Peter Claffey
- Harry Wild (Acorn TV) — the 'An Unhappy Happy is a Dangerous Thing' episode
Claffey turns up as Billy Lund, a cold-blooded killer who locks onto Jane Seymour's Harry like she is his intellectual match and drags the case out to feed his twisted little game. The episode kicks off with a loan shark named Ringo dying in nasty fashion, and things get darker from there. It is one of the show's bleaker chapters, and Claffey makes a very convincing villain. Ratings snapshot: Rotten Tomatoes 78%, IMDb 7.2/10. - Vikings: Valhalla (Netflix) — Season 3
With that frame, of course he wandered into Valhalla at some point. Claffey pops in as Dunstan across four episodes in Season 3 — brief, but a nice credential on a hit series. You could call it a warm-up lap before stepping into Westeros armor. Ratings: Rotten Tomatoes 96%, IMDb 7.4/10. - Bad Sisters (Apple TV+)
This one is fun: Claffey first shows up in the pilot season as Callum in the episode 'Explode a Man.' Then in 2024 the show brings him back playing a different character — Joe Walsh — who becomes the love interest of Becka, played by Eve Hewson. Season 2 drops the big personal twist: in episode 4, Becka knows Joe is the father of her pregnancy but only confides it to her sister; by episode 6, Joe finds out after that sister accidentally spills. Ratings: Rotten Tomatoes 88%, IMDb 8.2/10. - Small Things Like These (Hulu)
Claffey plays Barry in the period drama fronted by Cillian Murphy, with Game of Thrones alum Michelle Fairley also in the mix. It is a small role in a film that picked up serious acclaim for its acting and storytelling. Ratings: Rotten Tomatoes 93%, IMDb 6.7/10. - A Whistle in the Dark (stage)
After training at Bow Street Academy, Claffey made his professional stage debut in 2022 as Iggy Carney in Tom Murphy's bruiser of a play 'A Whistle in the Dark' — a piece that first premiered back in 1961 and still hits like a truck. He shared the stage with veteran actor Sean McGinley under director Jason Byrne, which is both a trial by fire and a great education. As he told the Irish Independent:'It is such an intense play and you could hear the audience gasp.'
So what is next?
HBO's A Knight of the Seven Kingdoms puts Claffey front and center as Ser Duncan the Tall — a wandering hedge knight with no patience for nonsense and the moral compass to match the reach. It is his biggest profile boost yet, and the timing makes sense after the mix of tough-guy roles, period grit, and stage intensity.
A Knight of the Seven Kingdoms premieres January 18, 2026 on HBO in the U.S. If you are curious how a former rugby forward handles no-helmet medieval chaos, this is the one to watch.