Hugh Hefner is mourning the death of his longtime secretary.
Mary O'Conner worked with the Playboy boss for 40 years.
Fans of the famed publisher got to know her as the comedic character running the Playboy Mansion and Hugh's business affairs behind-the-scenes on his US reality series Girls Next Door. The hit series followed the antics of Hugh's three girlfriends at the time.
Hugh took to Twitter late Sunday night to announce her passing.
"Mary passed away today. We loved her more than words can say," he wrote.
According to the New York Daily News, Mary had been suffering from poor health before she took a turn for the worse.
The cause of her death was unknown at press time.
Hugh's ex-girlfriends and former Girls Next Door stars Kendra Wilkinson and Bridget Marquardt also took to the micro-blog to share their condolences.
"RIP Mary O'Connor. She was an amazing person who helped me through so much. But I know she's happy with her boo Captain Bob. :)," Kendra wrote.
"Mary O'Connor will be missed.#RIPMary," Bridget added, thanking fans for their kind words.
Bridget, Kendra and their former Girls Next Door co-star Holly Madison have since moved out of the Playboy Mansion in Los Angeles.
Hugh recently settled down. He married Playboy model Crystal Harris on New Year's Eve. She is 60 years his junior at 26.
This is the third time ladies' man Hugh has been married, while it is Crystal's first union.
She had previously called off their June 2011 wedding five days before the ceremony but the pair reconciled last year.
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