The Complete Harry Potter Cast Twitter List:
J K Rowling [The Queen]
Harry Potter Film [The Official Twitter]
Pottermore [The Official Twitter]
The Magical SevenEmma Watson [Hermione Granger]
Tom Felton [Draco Malfoy]
Matthew Lewis [Neville Longbottom]
Evanna Lynch [Luna Lovegood]
Bonnie Wright [Ginny Weasley]
Dan & Rupert do not have Twitter accounts.
The WeasleysChris Rankin [Percy Weasley]
James Phelps [Fred Weasley]
Oliver Phelps [George Weasley]
The Other Cast MembersJessie Cave [Lavender Brown]
Natalia Tena [Nymphadora Tonks]
Katie Leung [Cho Chang]
Devon Murray [Seamus Finnigan]
Clémence Poésy [Fluer Delacour]
Freddie Stroma [Cormac McLaggen]
Warwick Davis [Prof. Flitwick/Griphook]
Stan Ianevski [Victor Krum]
Scarlett Byrne [Pansy Parkinson]
Afshan Azad [Padma Patil]
Jamie Campbell Bower [Gellert Grindlewald]
Anna Shaffer [Romilda Vane]
David Tennant [Barty Crouch Jr]
Angelica Mandy [Gabrielle Delacour]
Sean Biggerstaff [Oliver Wood]
Jason Isaacs [Lucius Malfoy]
The Next GenerationRyan Turner [Hugo Weasley]
Helena Barlow [Rose Weasley]
Arthur Bowen [Albus Severus Potter]
Will Dunn [James Potter]
Bertie Gilbert [Scorpius Malfoy]
The Past GenerationEllie Darcey-Alden [Young Lily Potter]
Alec Hopkins [Young Severus Snape] (OotP)
Benedict Clarke [Young Severus Snape] (DH2)
Rohan Gotobed [Young Sirius Black]
Let me know if I'm missing any, this thread will be for keeping up with their tweets
however with the lesser known cast members these tweets will be limited to tweets concerning Harry Potter