1. Emma Thompson as Sybill Trelawney
Where you know her from: Late Night, Last Christmas, and Nanny McPhee.
Fun fact: She also starred in Love Actually with fellow Harry Potter costar Alan Rickman.
2. John Cleese as Nearly Headless Nick
Where you know him from: Monty Python, Shrek, and A Fish Called Wanda.
3. Kenneth Branagh as Gilderoy Lockhart
Where you know him from: Murder on the Orient Express, Dunkirk, and Hamlet.
Fun fact: He was married to fellow Harry Potter costar Emma Thompson from 1989–1995.
4. Gary Oldman as Sirius Black
Where you know him from: The Dark Knight Trilogy, Darkest Hour, and Tinker Tailor Soldier Spy.
5. Ralph Fiennes as Lord Voldemort
Where you know him from: Maid In Manhattan, Grand Budapest Hotel, and Skyfall.
Fun Fact: He's costarring in Dolittle with fellow Harry Potter alumna, Emma Thompson.
6. David Tennant as Barty Crouch Jr.
Where you know him from: Doctor Who, Broadchurch, and Jessica Jones.
7. Robert Pattinson as Cedric Diggory
Where you know him from: The Twilight Saga, The King, and The Lighthouse.
Fun Fact: He's starring in Tenet with Harry Potter alums Kenneth Branagh and Clémence Poésy (Fleur Delacour).
8. Helena Bonham Carter as Bellatrix Lestrange
Where you know her from: The Crown, Fight Club, and Les Miserables.
Fun Fact: She used to date Harry Potter alum Kenneth Branagh from 1994–1999.
9. Rhys Ifans as Xenophilius Lovegood
Where you know him from: Notting Hill, The Amazing Spider-Man, and Snowden.
10. Bill Nighy as Rufus Scrimgeour
Where you know him from: The Best Exotic Marigold Hotel, Detective Pikachu, and About Time.
Fun Fact: He's one of the many Harry Potter alums that also starred in Love Actually.
11. Verne Troyer as Griphook
Where you know him from: Austin Powers and Fear and Loathing in Las Vegas.
12. Alfred Enoch as Dean Thomas
Where you know him from: Sherlock and How To Get Away With Murder.
Fun Fact: In all eight Harry Potter films, Alfred has less than eight lines. He spoke more in the pilot of HTGAWM than the entirety of Harry Potter.
13. Hero Fiennes-Tiffin as Young Tom Riddle
Where you know him from: After series.
Fun fact: He is the nephew of Ralph Fiennes, who played Voldemort as an adult.
14. Domhnall Gleeson as Bill Weasley
Where you know him from: Star Wars, Ex Machina, and The Revenant.
Fun Fact: He starred alongside Harry Potter alum Bill Nighy in About Time.
15. Natalia Tena as Nymphadora Tonks
Where you know her from: Game of Thrones, About A Boy, and Black Mirror.
16. Freddie Stroma as Cormac McLaggen
Where you know him from: Unreal, Pitch Perfect, and 13 Hours.
Fun Fact: He appeared in Game of Thrones along with fellow Harry Potter alumna Natalia Tena.
