SPOILER WARNING: This article contains spoilers for "International Iron Man" #6, which is on sale now.

Yep, Sir Elton John is "the guy in the duck suit." During his Central Park concert in 1980, John performed his encore in an elaborate Donald Duck costume -- a look that would become one of his signature stage costumes. You can see towards the end of this concert video. All this kinda makes sense since he's the guy responsible for superheroic song titles like "Someone Saved My Life Tonight" and "Saturday Night's Alright For Fighting."

It's highly unlikely that we'll get an "Elton John: Agent of S.H.I.E.L.D." series any time soon, but this is a fun reveal that has us wondering how many other musicians are secret agents in the Marvel U. The story of how Tony Stark's parents met continues in "Invincible Iron Man" #7, which arrives on September 21.