Bruno Mars
Mars was born Peter Gene Hernandez, though the "Grenade" singer has been Bruno his entire life. He was given the nickname as a toddler when his parents said he looked like wrestler Bruno Sammartino. However, he also thought his given last name would force him into the niche of Latin music, and that wasn't the angle he wanted to pursue.
Nicki Minaj
Rapper Nicki Minaj didn't even choose her stage name. Born Onika Tanya Maraj, she said "One of the first production deals I signed, the guy wanted my name to be Minaj and I fought him tooth and nail. But he convinced me. I’ve always hated it.”