PAUL SHAFFER as GEORGE COSTANZA
According to Paul Shaffer’s memoir, We’ll Be Here for the Rest of Our Lives, Jerry Seinfeld personally left a message stating that the role of George Costanza on his upcoming pilot was Shaffer’s if he wanted it. But Shaffer was preoccupied with his other work and said he never got around to returning Seinfeld’s call.
DANA DELANY as CARRIE BRADSHAW
Sex and the City creator Darren Star first offered the role of Carrie Bradshaw to his friend, Dana Delany. Delany had previously won two Emmy Awards for her portrayal of the compassionate nurse Colleen McMurphy on China Beach, but she was still smarting from the negative reviews she’d gotten for playing a dominatrix in the 1994 film Exit to Eden. She told Star that the public would never forgive her if she talked about sex onscreen again, so the part went to Sarah Jessica Parker.
JAYNE MANSFIELD as GINGER GRANT
Blonde bombshell (and mother of Law & Order: SVU star Mariska Hargitay) nixed the role of sexy Ginger Grant on Gilligan’s Island, stating “I am a movie star.”
PAUL GIAMATTI as MICHAEL SCOTT
As Bill Carter reported in the New York Times back in 2006, NBC executives had a strong favorite for the role of Michael Scott on the American adaptation of The Office—Paul Giamatti. He wasn’t interested, and the network eventually offered the role to Steve Carell.
STEPHEN TOBOLOWSKY as AL
Tim Allen’s Home Improvement sidekick was originally Glen, not Al. When the series was first being cast, character actor Stephen Tobolowsky was hired to co-host the fictitious Tool Time with Tim, but a previous commitment prevented him from appearing in the pilot episode. Richard Karn, a struggling actor, happened to meet Home Improvement’s casting director while attending traffic school and finagled an audition. Karn was invited to be Tobolowsky’s “placeholder” in the pilot, and then was asked to film a second episode when the series was picked up and Stephen was still off working on a different project.
MICHAEL RICHARDS as ADRIAN MONK
As Seinfeld was winding down its nine year run in 1998, the major networks were salivating to sign the series’ stars to new projects. ABC pictured Michael Richards as a bumbling Inspector Clouseau-type detective and pitched a premise about a cop suffering from Obsessive Compulsive Disorder. Richards, however, felt that the character of Adrian Monk didn’t offer enough comedic possibilities, so he passed. With Richards’ veto, ABC lost interest in the show and sold the rights to cable’s USA Network. Monk went on to become USA’s highest-rated show and Tony Shalhoub won three Emmy Awards.
See the rest at Mental Floss.