Jason Alexander Finally Reveals Why Susan Was Killed Off Seinfeld

If you know anything about Seinfeld, you'll know it'd be insane to share secrets that have been put in the vault. You can't open the vault — Once you open the vault, it ceases to be a vault.

But speaking on the Howard Stern show, Jason Alexander, most famous for playing show star George Costanza, has done just that, revealing the real reason why his character's love interest and fiancee, Susan, played by Heidi Swedberg, was killed off the mega-hit 90's show. 

In the episode which aired 19 years ago, Susan died after licking toxic wedding invitations, and Alexander revealed that the reason they went in that direction, which at the time received some negative feedback from fans, was that the cast had trouble working with her. 

"I couldn’t figure out how to play off her," Alexander admitted.

"Her instincts for doing a scene…were always misfiring. And she would do something…and then I’d adjust and then it would change…”.

While the 55-year-old actor stressed that he loved Swedberg as an actress, he conceded that the character was just not working on the show. 

"...What Heidi brought to the character is, we could do the most horrible things to her and the audience was still on my side and she wasn’t playing a bitchy character or anything but they knew it just wasn’t a good fit."

He revealed that his discontent went largely unnoticed for a while until fellow cast members Jerry Seinfeld and Julia Louis-Dreyfus shared some scenes with Swedberg and eventually they too shared Alexander's frustrations, admitting at a cast dinner one night: "You know what? It's fucking impossible!"

"Julia actually said, 'Don’t you want to just kill her?'" Alexander recalled, and that was that — show creator Larry David did the rest. 

Alexander again stressed it was not a reflection of Swedberg as a person however: "Every time I tell this story I cringe, because Heidi is the sweetest…"

Check out the full conversation below, but for now, it's going back in the vault and we're locking the vault — It's a vault.