Suggestions by @jsleister

Deaken Bluman

as Moaning Myrtle in Harry Potter (HBO Max Series)

Mark Addy

as The Fat Friar in Harry Potter (HBO Max Series)

Richard Wilson

as The Bloody Baron in Harry Potter (HBO Max Series)

Karen Gillan

as Lily Potter in Harry Potter (HBO Max Series)

Richard Madden

as James Potter in Harry Potter (HBO Max Series)

Peter Dinklage

as Professor Flitwick in Harry Potter (HBO Max Series)

Bill Paterson

as Tom the Innkeeper in Harry Potter (HBO Max Series)

Helen Mirren

as Professor McGonagall in Harry Potter (HBO Max Series)

Trevor Sellers

as Dedulus Diggle in Harry Potter (HBO Max Series)

Olivia Colman

as Aunt Petunia in Harry Potter (HBO Max Series)

Ian McNeice

as Uncle Vernon in Harry Potter (HBO Max Series)

Tilda Swinton

as Professor Trelawney in Harry Potter (HBO Max Series)

John Hurt

as Professor Binns in Harry Potter (HBO Max Series)

Sacha Baron Cohen

as Peeves the Poltergeist in Harry Potter (HBO Max Series)

Lisa Cholodenko

as Peeves the Poltergeist in Harry Potter (HBO Max Series)

Bill Nighy

as Garrick Olivander in Harry Potter (HBO Max Series)

Tom Hiddleston

as Professor Lupin in Harry Potter (HBO Max Series)

Ewan McGregor

as Gilderoy Lockhart in Harry Potter (HBO Max Series)

Rowan Atkinson

as Nearly Headless Nick in Harry Potter (HBO Max Series)

Andrew Scott

as Professor Quirrell in Harry Potter (HBO Max Series)