Eminem
Eminem's real name is Marshall Bruce Mathers III. When he was 14, he began rapping with a high school friend named Mike Ruby. The duo adopted monikers, Manix and M&M, which just stood for Marshall's initials.
Logic
Like most rappers, Logic's real name isn't Logic. It's actually Sir Robert Bryson Hall II. He was named after his father, but his mother added "Sir" to his first name. It has no meaning and is not a title like most people think.