The film, which is scheduled for release in 2011, will reimagine the series' main character, who is 10 years old, as a 23-year-old still clinging to the fairy godparents of his childhood. Alexander and Cheryl Hines will play the fairy godparents, Cosmo and Wanda.
Weber will play a villain in the movie. Daniella Monet will appear as a love interest.
Alexander, best known for playing George Costanza on the TV series "Seinfeld," won a Tony Award for Jerome Robbins' Broadway. Additional stage credits include Broadway Bound, Merrily We Roll Along, The Rink and the original Los Angeles company of The Producers, in which he played Max Bialystock. He is the artistic director of Reprise Theatre Company in Los Angeles.
"The FairlyOdd Parents" has been running on Nickelodeon since 2001. The series' creator, Butch Hartman, will executive produce the movie with Lauren Levine. Savage Steve Holland from a script by Hartman and Scott Fellows.