Suggestions by @jurassictransformers

Peter Dinklage

as Dr. Psychobos in James Gunn's Ben 10 (Season 1)

Wagner Moura

as Malware in James Gunn's Ben 10 (Season 1)

Matt Smith

as Psyphon in James Gunn's Ben 10 (Season 1)

Tony Todd

as Vilgax in James Gunn's Ben 10 (Season 1)

Ariana Greenblatt

as Young Kai in James Gunn's Ben 10 (Season 1)

Isabella Sermon

as Young Gwen in James Gunn's Ben 10 (Season 1)

Walker Scobell

as Young Ben in James Gunn's Ben 10 (Season 1)

Emma Roberts

as Sandra Tenyson in James Gunn's Ben 10 (Season 1)

Paul Rudd

as Carl Tennyson in James Gunn's Ben 10 (Season 1)

Harrison Ford

as Wes Green in James Gunn's Ben 10 (Season 1)

Mark Hamill

as Max Tennyson in James Gunn's Ben 10 (Season 1)

Grant Gustin

as Rook Blonko in James Gunn's Ben 10 (Season 1)

Finn Wolfhard

as Kevin Levin in James Gunn's Ben 10 (Season 1)

Isabela Merced

as Kai Green in James Gunn's Ben 10 (Season 1)

Millie Bobby Brown

as Gwen Tennyson in James Gunn's Ben 10 (Season 1)

Asher Angel

as Ben Tennyson in James Gunn's Ben 10 (Season 1)

jurassictransformers

as Writer in James Gunn's Ben 10 (Season 1)

Man of Action

as Producer in James Gunn's Ben 10 (Season 1)

James Gunn

as Director in James Gunn's Ben 10 (Season 1)

Gemma Chan

as Alien in Actors who should join certain big franchises