Many of our favorite actors become forever linked to an iconic role ― especially when it’s a television show, and we see them as that character for years on end. How could there be a Tony Soprano without James Gandolfini, or a Buffy The Vampire Slayer without Sarah Michelle Gellar? (We’re still pretending the Kristy Swanson movie never happened.)

But of course, few TV characters are created with the actor who ends up playing them in mind. Many shows go through an exhaustive casting process to find just the right fit ― and some of the actors who almost get cast are pretty famous in their own right. A recently-leaked sign-in sheet for The Office revealed that familiar faces like Hamish Linklater and Adam Scott were considered for the role of Jim (ultimately going to John Krasinski, of course, making him a star), while Paul Giamatti was the first choice for the role that went to Steve Carell.

From big stars who turned down TV projects that ended up being a huge deal to then-unknowns who went on to find fame in future shows, here are TV's most alarming casting near-misses from some of our favorite shows to ever grace the small screen!

He became a werewolf, she became a witch and a lesbian. One of Buffy The Vampire Slayer's cutest couples has some serious odds stacked against them, but finally Oz and Willow are back together!

Or at least the stars who played them are, since Seth Green is guest starring on Alyson Hannigan's CBS sitcom How I Met Your Mother.

Find out more (and see another pic of the awesome twosome) after the jump!