70 suggestions

Cillian Murphy
as Servious Snape in Harry Potter (Recasted)

Patrick Stewart
as Albus Dumbledore in Harry Potter (Recasted)
Stephen Fry
as Albus Dumbledore in Harry Potter (Recasted)

Katie McGrath
as Bellatrix Lestrange in Harry Potter (Recasted)
Lesley Sharp
as Sybil Trelawney in Harry Potter (Recasted)

Tilda Swinton
as Sybil Trelawney in Harry Potter (Recasted)

Rory McCann
as Rubeus Hagrid in Harry Potter (Recasted)

Mark Addy
as Rubeus Hagrid in Harry Potter (Recasted)

Blake Ritson
as Severus Snape in Harry Potter
Stephen Fry
as Albus Dumbledore in Harry Potter