Suggestions by @optimistic_writer

Ewan McGregor

as Starman in Earth-2 (2040)

Colin Farrell

as Wildcat in Earth-2 (2040)

Jude Law

as Green Lantern in Earth-2 (2040)

Chris Pratt

as The Flash in Earth-2 (2040)

Gillian Anderson

as Wonder Woman in Earth-2 (2040)

Gerard Butler

as Batman in Earth-2 (2040)

James Marsden

as Superman in Earth-2 (2040)

Brad Bird

as Writer in Earth-2 (2040)

Brad Bird

as Director in Earth-2 (2040)

Anya Taylor-Joy

as June Robbins in Challengers of the Unknown (2040)

Jim Carrey

as Walter Mark "Prof" Haley in Challengers of the Unknown (2040)

Brad Garrett

as Leslie "Rocky" Davis in Challengers of the Unknown (2040)

Charlie Cox

as Matthew "Red" Ryan in Challengers of the Unknown (2040)

Brian Austin Green

as Kyle "Ace" Morgan in Challengers of the Unknown (2040)

Peyton Reed

as Writer in Challengers of the Unknown (2040)

Peyton Reed

as Director in Challengers of the Unknown (2040)

Taye Diggs

as Hardware in Hardware (2039)

Blair Underwood

as Icon in Icon (2039)

Mahershala Ali

as Black Lightning in Static (2038)

Caleb McLaughlin

as Static in Static (2038)