There is only one person who could replace Simon Cowell on "American Idol" ... someone famous, someone critical, and someone with a penchant for tight clothing ... someone like Ryan Seacrest.
A TMZ user named April made the suggestion on Thursday's TMZ Live -- and when we got to thinkin' ... it made perfect sense.
Seacrest knows the show -- he knows the music -- and he has a great rapport with the rest of the judges.
Plus, it would be way easier to plug in a new host than force another awkward, unfamiliar person to sit at the judges' table .... we're talkin' about you Kara.
So we gotta ask ...