That's a great thread. Being a big boxing and MMA fan, I've actually given this some thought before.
I would be one of those fighters that walk in to a different walkout tune every time, but it has to be chosen based on the situation. So if I'm embroiled in a heated rivalry with the guy I'm fighting I'll walk out to Dexter's blood theme:
Quite menacing and impactful. Either that or "The Rains of Castamere." Game of Thrones fans will get it:
If I'm challenging for the title, then this is a no-brainer:
If it's just any fight, I'd still want something intimidating so I gotta go with this:
And if I ever happen to break my "only instrumental walk out tunes" gimmick then I'll just go with Simple Man by Lynyrd Skynyrd:
So as you can see, I've got my imaginary career as a prize fighter all figured out.