Here is who I will cast as uncasted Marvel Character in post Infinity War
Black Widow
Adam Driver as Victor Von Doom/ Doctor Doom- Doom will not yet be`the Doom in the Comics who rules over Lavtveria, But a Jihadi John Style Hydra terrorist who is secretly working for Dormammu called Hydra Doom. he wears a Balaclava to hide his face and his face is never seen. In the end comfrontation with Black Widow, Doom is gravely injured and Burned (Similar to that of Vader in Revenger of the Sith but worse) and uses his magic to survive. in the end credit scene of the Black Widow movie, A Hydra rescue team lead by Zemo rescues Doom and places him in a medical capsule.
Fantastic Four
Matt Smith as Reed Richards Mr Fantastic
Lily James as Sue Storm/ Invisible Woman
Robert Kazinsky as Ben Grimm/ The Thing
Bradley James as Johnny Storm/ Human Torch
Hanah Spearitt as Alicia Masters
Robert Llewelyn as Harvey Elder/ Mole Man
Sacha Baron Cohen as Bentley Wittman/ Wizard- I think The Wizard and the Frightful Four are appropriate villains for the first Fantastic Four movie as Medusa of the Inhumans is a member. It was Bentley Wittman who is the CEO of Wizard Enterprises who funded the Fantastic Fours space voyage which gave them their powers, The voyage left Wittman Bankrupt and his fame was overshadowed by the Fantastic Four, so he seeked revenge by becoming the Wizard using an Iron Man Suit that was given to him by Tony Stark, Kidnapped and Brianwashed Medusa, and recurited Trapster and Klaw.
Chris Barrie as the Impossible Man- He will make his debut appearance in the second Fantastic Four movie in the MCU which focuses on the Skrulls trying to invade earth as their planet was destroyed by Galactus (Who will be the villain in the 6th Avengers Movie) . After the film he will have his own spinoff tv series which will have a very similar format to the Doctor Who spinoff Sarah Jane Adventures.
Inhumans
John Barrowman as Black Bolt
Kara Tointon as Medusa
Hannah Tointon as Crystal
Riz Ahmed as Karnak
Samuel Anderson as Triton
Temuera Morrison as Gorgon
Harry Lloyd as Maximus the Mad
Matt Lucas as the voice of Lockjaw
Spiderman
James Nesbitt as Norman Osborn/ The Green Goblin- Watch Nesbitt as Jekyll in the series of the same title and you will see why he should play Norman Osborn.
Steve Pemberton as Dr Otto Octavius/ Doctor Octopus
Mark Gatiss as Dr Curt Conners/ Lizard
Dr Strange 2
Julian Bleach as Nightmare
Guardians of the Galaxy 3
Nicholas Briggs as the Supreme Inteligence- This film will focus on the Kree empire trying to invade Xandar after the Kree Home planet was destroyed by Galactus. So the Kree Clone Ronan and the Guardians once again stop the Kree.
Peter Kay as Mojo- I think It would be a good idea if Fox could lend Mojo to Marvel to use him as a cameo in Guardians
Avengers: Kree/ Skrull War
Neve Mcintosh as Veranke
Avengers: Galactus
Gabriel Woolf as the Voice of Galactus
Paul Bettany as Norin Radd/ Silver Surfer
And as for Tv here is my other castings
Noel Clarke as Blade