Suggestions by @ringothedrummer

Jason Isaacs

as The Master in Doctor Who (Season B)

Michael Sheen

as The Monk in Doctor Who (Season B)

Alex Kingston

as River Song in Doctor Who (Season B)

Nicholas Briggs

as Cybermen in Doctor Who (Season B)

Jonathan Watson

as Commander Tennak in Doctor Who (Season B)

John Leeson

as K-9 in Doctor Who (Season B)

Emma Thompson

as Professor Madeline Whittaker in Doctor Who (Season B)

Josh O'Connor

as Casey Davies in Doctor Who (Season B)

T'Nia Miller

as The Doctor in Doctor Who (Season B)

Jack Nicholson

as King Koopa in Super Mario Bros. (Second Draft)

Jake Gyllenhaal

as "Griffin" in Dark Universe (Season Three)

Spoiler

as "Griffin" in Dark Universe (Season Three)

Andy Serkis

as Dr. Henry Jekyll in Dark Universe (Season Three)

Daniel Brühl

as Dr. Victor Frankenstein in Dark Universe (Season Three)

Chiwetel Ejiofor

as Adam in Dark Universe (Season Three)

Adrien Brody

as R. M. Renfield in Dark Universe (Season Three)

Scott Eastwood

as Quincey Morris in Dark Universe (Season Three)

Callum Turner

as Arthur Holmwood in Dark Universe (Season Three)

Hugh Bonneville

as Dr. John Seward in Dark Universe (Season Three)

Mia Wasikowska

as Lucy Westenra in Dark Universe (Season Three)