Harris's own character Lane Pryce was dramatically killed off in Mad Men's latest episode 'Commissions and Fees' when his embezzling was discovered by Don Draper (Jon Hamm).
The actor has now claimed that Moss is leaving Mad Men as well following her character Peggy Olson's decision to quit Sterling Cooper Draper Pryce earlier this season.
"Actors are always ending jobs. It isn't a big deal in that sense. Also other people had left the show that had been there since the beginning," Harris told The Daily. "Elisabeth [Moss] left the episode before and she'd been there since the beginning.
"Michael Gladis (Paul Kinsey) left in season three [though reappeared for one episode this season]… Bryan Batt. People leave and it's just part of it. They didn't make a giant fuss."
Moss's representative remained coy on the actress's future on the series, telling TV Guide: "The season isn't even over yet."
AMC offered no comment on Harris's remarks.
Moss has played secretary-turned-copywriter Peggy Olson on all five seasons of the award-winning Mad Men.
The star recently explained that she is very pleased with how much Peggy has evolved over the course of the AMC series.
"I've known Peggy for six years. What's great about that is when I started out I was 23 and now I'm 29, so I've changed a lot in six years," Moss said in May.
"So the sort of melding and blending of you changing and you growing up and the character changing and melding and growing is not an opportunity that you always get."
Mad Men wraps up its fifth season on AMC on Sunday (June 10). The show airs on Sky Atlantic in the UK.
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