Those with nipples numbering in the triples — and beyond.
"It's actually the size of an infant's nipple," explained actor Mark Wahlberg about his third nipple in an interview with Nova FM. According to the actor, it's located just below his adult-sized left nipple.
In 2012, model and "Real Housewives of Miami" star Joanna Krupa revealed to the Huffington Post that she has a third nipple. "It looks more like a mole, but my doctor said it's an actual third nipple," she confessed.
English recording artist Lily Allen makes no secret about her third nipple, and she once let the host of a Dutch television show touch it on camera. "It gets hard when you touch it," she laughed.
Harry Styles (left) of the pop group One Direction confirmed to Nova FM that he has not only one extra nipple, but two. "They're a bit smaller than the other ones," he was quick to point out. "I don't look like a cow or anything."
According to author Mitchell Symon's book "Celebrity Lowdown," Oscar-winning actress Tilda Swinton was born with a third nipple. It's also discussed in a Channel 4 documentary titled "The Triple Nipple Club."
Back before Carrie Underwood was a country star, she was a hopeful on "American Idol." During her audition, Simon Cowell asked her about a rumor he'd heard, and she confirmed to the judges that yes, she was born with a third nipple. "It just looked like a mole," said Underwood. She then explained how it made her feel self-conscious, which is why she had it removed.