I’d want an anthropologist who knows everything about hand-building boats from available materials.
Archeology professor Dr. Indiana Jones? He might be able to get us off of there.
I choose Dr. Doom. His citizens would find him sooner or later.
Only if you’re a young, attractive woman. Otherwise you’re just asking to be chewed up by a mechanical Easter Island head or cut to pieces by undead sand crabs.
Geez, doesn’t anyone have a PhD in Island Survival or something?
Preferably hot and female?
Marine biology
What if I’m the lovable sidekick? He wouldn’t have the heart to see me die then.
Olivia Judson
Not that I’d be trying to get off the island.
Of course! Re-reading the OP, I see that the requirements are “stuck indefinitely” on the desert island. I change my answer to nuclear physicist Dr. Christmas Jones (from James Bond - The World Is Not Enough).
Damn. Nice call.
I’d like to get a look at her bromeliads.
I’ll go with Richard Feynman as well. He was sharp and practical, so he could help get stuff done, then we could talk physics, and then argue about gender stuff. Letch isn’t necessarily a bad thing in this situation either.
I only worry that he may have been a bit too much of a pompous jerk sometimes.
I don’t know, but it’d have to be a sexy botanist, preferrably specializing in the region of the island. 
Damn right. The world’s second hottest biologist.
And the first would be?