What if the characters from 1969 Collinwood played the parts on Gilligan's Island.  Who would play what part?  Here's how I would cast them:

Barnabas - The Skipper
Willie - Gilligan
Roger - Mr. Howell
Elizabeth - Mrs. Howell
Maggie - Ginger
Vicki - Mary Ann
Prof. Stokes - The Professor

You might be able to cast Julia as Gilligan because she became more of a partner to Barnabas than Willie did.  You might also be able to cast her as the Professor.

On Star Trek it would be:

Barnabas - Captain Kirk
Prof. Stokes - Mr. Spock
Julia - Dr. McCoy
Burke - Scotty
Vicki - Uhura
Maggie - Nurse Chapel
Joe Haskell - Sulu
Chris Jennings - Chekov

In addition to the main characters there are those who only appeared in one episode.

On Gilligan's Island:

Adam - Tongo the ape man
Dr. Lang - Mad Scientist Boris Ballinkov who switched the castaways minds and bodies with each other.
Laura - Erika Tiffany Smith (played by Zsa Zsa Gabor in real life)
Matthew Morgan - Wrong Way Feldman

On Star Trek:

Elizabeth and Roger - Spock's mom and dad
David - Child alien who ran a huge starship by himself (played by Clint Howard in real life)
Angelique(Cassandra) - Female Romulan Captain (played by Joanne Linville in real life)
Leviathan Monster - Silicone based monster who terrorized the miners on the Janus 6 colony.

These lists can go on and on and the whole exercise can be repeated with the characters from 1795, 1897, 1840, PT, etc.