Out of Keoghan's filmography, the 2016 movie Mammal is quite underrated. Directed by Rebecca Daly (Good Favour), the international title follows a woman named Margaret (Rachel Griffiths) who is lost in the world. She left her husband and son years ago and is kind of just skating by in life in isolation. That is, until she learns her son has died and she forms an unlikely connection with a homeless teenager she finds outside her house.
This teen, named Joe, is played by Keoghan.
While Mammal is hardly one of the best movies I've ever seen, Griffith and Keoghan give stellar performances worth talking about. Both of their characters are pained by their pasts and the current trauma they face, and even if they don't talk about it, they relate to one another and develop a connection. Keoghan gives such a subtle performance as a detached, lonely teenager who's neither good nor bad.
Where to watch: Watch on Dailymotion or Rent on Amazon Prime Video in the UK for £1.99
6. The Batman
Keoghan might only appear in 2021's The Batman for a quick moment, but it's still one of the better movies on his resume. Directed by Matt Reeves (Cloverfield), the latest Batman installment stars Robert Pattinson as the Caped Crusader, with a fantastic supporting cast consisting of Zoë Kravitz as Catwoman, Paul Dano as the Riddler, Colin Farrell as the Penguin, and other talented actors.
Leaning into his detective side, The Batman sees the titular character follow clues to find Gotham's latest villain, a serial killer called the Riddler. Pattinson does a great job bringing one of the most iconic comic book characters to life, and while the movie certainly has its faults, the cast is one of the strongest parts about it. The action and cinematography are also great.
Keoghan makes a cameo appearance at the end of The Batman as an "Unseen Arkham Prisoner," a.k.a. the Joker. While we don't see much of him, a later-released deleted scene proves he's got the acting chops to reprise the role, if that's the plan for the upcoming sequel.
Where to watch: Stream on Max or on Netflix