Jason Alexander apologized on Thursday to Heidi Swedberg, who played Susan Ross, fiancee of his "Seinfeld" character George Costanza, after telling an anecdote some took as deprecating during an interview on Howard Stern's radio show.

"To Heidi, I personally apologize," Alexander, 55, tweeted. "You are a sweetheart."

The comedian's anecdote, told Wednesday on Stern's Sirius XM show, focused on the difficulty of the two meshing their comedic styles. He also quoted co-star Julia Louis Dreyfus saying, "Don't you want to just kill her?" -- a reference, Alexander explained in his tweet, to the character, not the actress.

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"I told the story to try and clarify that no one wanted to kill Heidi," wrote Alexander, who succeeds "Seinfeld" creator Larry David in Broadway's "Fish in the Dark" on Tuesday. "I and the cast really liked and like Heidi. She is a kind, lovely person who undoubtedly worked really hard to create Susan and that character was clearly what Larry and Jerry [Seinfeld] wanted her to be for George."

He went to on say, "They were always looking for an inventive end to the engagement. So when the comment was made about 'killing,' no one was talking about the actress -- they were talking about the character. And that made a creative lightbulb go off, apparently."

The Susan character eventually died after licking toxic glue that was on cheap wedding invitation envelopes.

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Calling Swedberg, 49, "generous and gracious," he said, "I am so mad at myself for retelling this story in any way that would diminish her.' "

Swedberg's representative did not respond to a Newsday request for comment.