David Ogden Stiers as Santa Claus
and
Kristen Wigg as Mrs. Claus
2 words- Stephen Colbert.
Honestly, I’d be very intrigued if Catherine Zeta-Jones was cast as a lead lady in a Pixar project.
Natalie Portman’s voice is kinda cute. She could be a female lead.
Honestly, I’m very hopeful that Craig T. Nelson might be in another Pixar film. It seems unlikely beyond question, and a random idea, but his voice is awesome.
I second that! I was watching a video of her on Seasame Street. I like her voice a lot.
If Pixar ever had Stephen Colbert or Jon Stewert provide their voice, I’d be sooooo happy! Tina Fey would be another good choice too.
I would love if Pauley Perrette did a Pixar film 
!
I’m not familier.
She plays my favorite character from NCIS: Abby. She’s basically awesomeness in a can 
. I think she’d be epic in a Pixar film.
Abby: en.m.wikipedia.org/wiki/Abby_Sciuto
Pauley Perrette: en.m.wikipedia.org/wiki/Pauley_Perrette
Looking back at earlier posts to see if any have been fufilled. This came close! Neil was originally cast for the Good Dinosaur but was recast.
Rachel McAdams
I’d like to see Rowan Atkinson (Mr. Bean), Jim Carrey, or even Melissa McCarthy
Rita Ora
How about a movie starring all three of them?
Just saw your post, an amazing idea! 
If I could pick an actor to appear in any future Pixar films, I would pick Harrison Ford, Christopher Lloyd, Sissy Spacek, Drew Barrymore, and even the former Python members, you know, like John Cleese and Eric Idle.