Thundarr The Barbarian would make a great movie! I've actually started a very similar thread on another website. Here's who I think should play each character...
Thundarr The Barbarian
Kevin Sorbo: He has the right size, build, and look. He also did quite a good job in Kull The Conqueror and Hercules: The Legendary Journeys. His hair's the wrong colour, but it can be dyed.
Tyler Mane: Also the righ size, build, and look, he has the added advantage of having blonde hair. While his roles in X-Men, Halloween, and The Black Mask 2, weren't all that challenging, he did quite well as Hardcore in How To Make A Monster. I think he's ready to take the next step in his career.
Bottom Of The Barrel: Dulph Lundgren (He-Man in Masters Of The Universe), Vin Diesel (XXX in XXX), Kane Hodder (Jason Voorhees in Friday The 13th Part VII - X), Bill Goldberg (one of the UniSols in Universal Soldier 2), "Big Poppa Pump" Scott Steiner (former WCW World Heavyweight Champion), and Carrot Top. All of these guys are the right size, build, and have the right look for the role. Unfortunately they're all either too old or/and have questionable acting abilities.
Princess Ariel The Sorceress
Tia Carere: She's beautiful. She's Asian. She's athletic. She's played both a scholar (on Relic Hunter) and a sorceress (in Kull The Conqueror), and played them both very convincingly. I think she'd make a great Ariel.
Lucy Liu: Just as beautiful, Asian, and athletic as Tia Carere, she's also slightly better known due to her more successful film and TV career. I think Tia Carere looks more like Ariel, but Lucy Liu would probably draw a larger fanbase.
Kristin Kruek: She's beautiful, she's Asian (half white/half Chinese), and a good actress. She's played Lana Lang on Smallville for years, as well as Fiona on Eurotrip. I think she'd be great in the role.
Ookla The Mok
I wouldn't make Ookla a CGI character, that would just suck. I would find a really large actor and put him in a mok suit, much like what was done for Chewbacca in the Star Wars saga. Here are my choices for Ookla...
"The Big Show" Paul White: He's 7'2", weighs 500 lbs, and acted in Adam Sandler's The Water Boy (as Captain Insano), and Star Trek: Enterprise (as an alien). Also, he was a fan of Thundarr when he was a kid.
"The Geat Khali" Dalib Singh: He's 7'4", weighs 425 lbs, acted in Adam Sandler's remake of The Longest Yard and Steve Carels Get Smart. His English is atroacious, but that will only help the other actors during filming.
"El Gigante" Jose Gonsalez: He's 7'7", weghs about 450 lbs, and he's acted in Hercules In The Underworld and on an episode of TV's Baywatch. When he used to wrestle for the WWE as The Giant Gonsalez he used to have to dress up like a sasquatch. His English is almost as bad as The Great Khali's, but again that might be a good thing. Only real problem is I heard he retired from wrestling because of bad knees, so that might interfere with any action scenes.
Gemini or Sabien The Wizard
Gary Oldman: He played an excellent villain in both The Professional and Bram Stokers Dracula. He's very good at being sinister.
Michael Ironside: Playing villains is pretty much Michael Ironside's bread & butter. He's been the villain in The Watcher, Scanners, Highlander 2: The Quickening, Young Blades, just to name a few. Even his good guy characters have a somewhat sinister edge to them, like his character Tyler on V: The Miniseries and V: The Final Battle.
Kevin Spacey: A brilliant actor, he did a great job as John Doe in SE7EN, and as Kaizer Sosser/The Gimp in The Usual Suspects, as well as Lex Luthor in Superman Returns. He doesn't quite have the perfect look for the role the way Michael Ironside does, but he's close.
Writers
John Milius & Buzz Dixon: Buzz Dixon wrote the scripts for many of the episodes of Thundarr, and I understand he's already written a script for a feature length Thundarr movie. John Milius wrote and directed Conan The Barbarian, and did an awsome job too.
Oliver Stone: He cowrote Conan with John Milius. They were a great team then, they could be a great team again.
Directors
Peter Jackson: The reason? Five words. The Lord Of The Rings. 'Nuff said.
Steven Spielberg: The reason? Two words. Jurassic Park. 'Nuff said.
John Milius: The Reason? Three words. Conan The Barbarian. 'Nuff said.
Jerry Bruckheimer: The reason? Five words, The Pirates Of The Caribbean. 'Nuff said.
Other Directors: Ron Howard (Willow), and Rob Reiner (The Princess Bride). Both would do a more than adequate job. The one person who should never, ever,EVER, direct Thundarr is George Lucas. He'd just stick our three heroes, the chief villain, and a handful of extras in front of a green screen and add everything else with CGI. After the monumental failure of the Star Wars prequals, you'd think he'd learn his lesson. But he still insists that they're the best work he'd ever done.
EXECUTIVE PRODUCER
I only have one choice for this one... George Lucas. I don't want him directing the movie, he would be perfect to bankroll the project. First of all, the Star Wars and Indiana Jones franchises have made him into a multibillionaire. Secondly, as his crappy Star Wars prequels prove, he'd be willing to finance just about anything. Third, with the similarities between Sun Swords and lightsabers, as well as wookiees and moks, any copy right arguments will be averted. Also any sound effects from the Star Wars archives could be used in the movies (lightsabre sound effects and wookiee speak).