Okay, we know that's a weird question, but hey, we're just being honest. His legal name is Adam Richard Wiles.
Luckily, Selena Gomez has our back. During a recent interview, she let the cat out of the bag, and revealed that Tay Tay does NOT call Calvin, Calvin.
New Zealand radio's "The Edge Afternoons" asked Selena if Zedd would be embarrassed that she refers to him by his real name, Anton.
"I don't know, maybe!" she admitted. "But I made this a deal. I said it to Calvin Harris too. I was like, 'Look, you guys have two names. It really is frustrating. I need to know which name I should call you because I don't know what is what. So I speak with the real names. Adam and Anton."
The radio hosts were flabbergasted that Calvin Harris isn't the Scottish DJ's real name, and they asked Selena if they call him "Adam Harris." "No, I don't think that's his last name!" Selena said. "I don't know his last name."
His last name is Wiles. Why don't you know that, Sel? He's dating your BFF, girl!
Now the real question is, what is Taylor and Calvin's (ahem, Adam's) new couple name? Taydam? Swiles?
This isn't the only thing Sel revealed during this interview, either. Find out if she REALLY dated Zedd, here.