Mark Zuckerberg said he's the most well-known millennial in a newly revealed email. So, is he?

• Mark Zuckerberg said in a newly revealed email, "I am the most well-known person of my generation."
• It's a bold statement, and it might be true.
• But is he more popular than Taylor Swift and Cristiano Ronaldo? It's basically impossible to know.

Mark Zuckerberg, who just celebrated his 40th birthday, is a millennial. But is he the most famous millennial? He thinks so.