Famous is an adjective, not a noun, so it would have no plural.
Adjective have degrees:
The adjective 'famous' can describe a singular or a plural noun:
The plural way to spell studio is studios.
The plural is cantaloupes.
The plural is "emeralds."
The plural is roses.
The plural of beach is beaches.
The plural of celebrity (famous person) is celebrities.
The correct spelling of the plural noun is celebrities(famous or well-known people).
The plural of parcel (package, section of land) is parcels.The plural of parasol (sun umbrella) is parasols.The famous NFL football coach is Bill Parcells.
The plural way to spell studio is studios.
The plural is hooves.
The plural is cherries.
The plural is cantaloupes.
The plural is resources.
The plural is "emeralds."
The plural is roses.
The plural is bridges.
Trout is plural