As many have pointed out, Indiana Jones and Back To The Future, simply because those movies have way more characters on offer than just Indy and Marty & Doc, respectively.
James Bond, because I'd like all 007 actors to be featured.
Also, we have only got one Bond Girl, and she was dead. Great female representation, really...
Since 24 films gives us a lot of characters, I think the most obvious ones would be
The remaining James Bonds (Lazenby, Dalton, Brosnan, Craig)
M (Bernard Lee and Judi Dench)
Q (Desmond Llewelyn and Ben Wishaw)
Villains: Dr. No, Goldfinger, Scaramanga, Drax, Zorin, Sanchez, Trevelyan, Le Chiffre, Silva
Girls: Honey, Tatiana, Pussy Galore, Tracy, Solitaire, Anya, Octopussy, Kara, Natalya, Onnatopp, Elektra, Vesper, Severine, Madeleine
The Muppets, because yes, I really do need a 10 inch Sweetums, thank you very much.
Pirates of the Caribbean, because we have gotten 4 versions of Jack, but not a normal Will? Bit unfair... And we haven't gotten a Norrington, Gibbs, Governor Swann, Beckett, Bootstrap Bill.. And imagine Pop Rides with all the ships!