Then we found out he's going to be the father to New York socialite Lauren Silverman's baby—which provided yet another shocker, since she's still technically married to his friend and real-estate mogul Andrew Silverman. But during what a source tells E! News has been "a messy split," Simon "became a shoulder to cry on for her."
And although, the X Factor judge's news was unexpected, he's not the first star to drop a baby bombshell! Here are 6 more surprise celeb dads...
1. Jude Law: In 2009, a rep for the divorced, then-father-of-three announced that another baby was on the way. After a one-nighter with aspiring actress/model Samantha Burke, Law learned that she was pregnant with their child. A DNA test confirmed the paternity, and Law vowed to support the baby Sophia, who was born in September 2009 without her father by her side.
A month later, mother and daughter posed for the cover of Hello!, and at the time of the magazine's publication, Jude had still not met his daughter.
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2. Gavin Rossdale: This is a one-night stand the rock star will never forget. After having a fling with singer Pearl Lowe when they were both in their late teens, Rossdale found out (many years later) that he is the father of Lowe's daughter, Daisy. Ironically enough, the duo stayed close, and the Bush frontman was named the girl's godfather.
Except now, he can drop the god part.
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3. Hugh Grant: The actor had a "fleeting affair and while this was not planned" he became a dad. After having a short relationship with Chinese actress Tinglan Hong, Grant became a father to a baby girl named Tabitha.
His rep told E! News at the time, "He and the mother had a fleeting affair and while this was not planned, Hugh could not be happier or more supportive. He and the mother have discussed everything and are on very friendly terms."
"I like my daughter very much. Fantastic. Has she changed my life? I'm not sure. Not yet. Not massively, no. But I'm absolutely thrilled to have had her, I really am. And I feel a better person," he said about being a dad.
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4. Ryan Phillippe: After having a summer romance with Alexis Knapp, the actor's ex-galpal informed him that she was pregnant with his child in the fall of 2010. Phillippe was so sure he was the father, that he didn't bother taking a paternity test and even showed up at the hospital for the birth.
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5. Benicio Del Toro: One of the most shocking baby announcements in the past few years (maybe even ever) was Kimberly Stewart pregnant with Del Toro's child.
"Kimberly is pregnant," Del Toro's rep confirmed to E! News. "Benicio is the father and is very supportive. Although they are not a couple, they are looking forward to the arrival of the baby."
The pair, who never even a pair, continue to coparent their daughter Delilah, who was born in Aug. 2011.
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6. Eddie Murphy: After splitting from ex-wife Nicole Mitchell, whom he has five children with, the actor started hooking up Melanie Brown aka Scary Spice. Months later, the singer announced that she was pregnant and claimed Murphy was the father, but he denied the claims until a paternity test was done. Sure enough, Angel Iris is his daughter.