What celebrities would you like to see in new episodes?
Johnny Depp
Orlando Bloom
Angelina Jolie
Daniel Radcliffe
Beyonce Knowles
Arnold Schwartzenegger
Chris Rock
Halle Berry
Andy Serkis
just to name a few.
To be fair What's New Scooby Doo (since it actually respected the Scooby's before it) had a couple guest stars i some the episodes to mix it up. Sometimes it was short but it was cool to see them do some of that
I refuse to argue on IMDB until the general populous actually uses their brains
Not most of the ones listed above. They mostly used comedic actors or musicians. I don't think dramatic/action actors and especially reality stars would work. They did a good job of mixing in a few older people (they also used 'dead' people like Laurel and Hardy and Three Stooges, voiced by others). And included some cartoon characters from other shows.
I'd go with (some of these I wouldn't care to see, but kids probably would...and some would be a stretch given the person's reputation):
Jim Parsons
Jerry Seinfeld
Jonas Brothers
Betty White
Roseanne
Miley Cyrus
Gary Busey
Jon Stewart
Stewie & Brian Griffin
Carrot Top
Ones I wish they had done back then:
Carol Burnett
Casey Kasem (that would have been funny!)
Bea Arthur
I think Betty White and Roseanne would do it, Betty White even then.
Stewie and Brian, forget it. I just envision McFarlane wanting his characters to make too many ridiculous juvenile jokes at the Mystery Machine gang's expense.
Carrot Top, doubt it, but he may be inclined and behave himself.
Busey I don't think would be agreeable.
Parsons might, even at this point of his success.
Jonas Brothers might, I wouldn't want to see Miley Cyrus here. Her dad did the intro to a movie, so he might.
As the other poster said, you'd have to take into consideration who would 'transfer well' in animated form.
Of your list, I think Arnold and Chris Rock stand the best chance.
Beyoncé, if she did it, would probably be as big a surprise as Cass Elliott is in the first series; she ran with Shaggy and Scooby and made fun of her weight.
To journey with Shaggy and Scooby meant you had fun running from the ghosts. To go with Fred, Velma and Daphne meant you found boring clues.
The others I think would run into conflict of one kind or another; considered it beneath them, didn't like the way they were written into the show, etc.
I think it was a Tiny Toons that sought to 'recapture' the old Merrie Melodies with the 'Hollywood canteen' and cameos by celebrities. Among them shown that I recall were Meryl Streep and Michael Keaton.
Of plausible celebrities of the past forty years since the first Scoobie movies, I would have to say it might be cool to have seen:
Jim Carrey
Robin Williams
Whoopi Goldberg (she'd be very agreeable)
With the Batman and Robin teamups, that opens the door to all the Marvel comics characters; Spiderman, Xmen, Avengers, etc.
I daresay there would have been a Superman encounter as well.
Wonder Woman made her first animated appearance on an episode of The Brady Kids, so any hero would probably consider Scooby Doo a step up from that arena.