If the other thread names haven't made that clear, put the alias first, and their actual name in parenthesis. If they have no alias, just plainly put their real name.

For example...
• Spider-Man (Peter Parker)
• Batman (Bruce Wayne)
• Voldemort (Tom Riddle)

What if they changed their birth names?
Put the name they changed it to.

What if they see their alias as their true selves, in a deep level of identity?
No, just stop. Put the legal name in the parenthesis.