No. Sean Penn is not part of the 1979 The Warriors.
It was Luther (played David Patrick Kelly) who’s a dead ringer for Sean Penn, that you might be thinking of.
Kelly who has been previously branded as Sean Penn’s clone, Sean Penn's uglier brother (who isn't Chris Penn) and Sean Penn's doppelganger, appeared the in cult classic The Warriors.
It was his first major scumbag role which cemented the immortal cry: “Warriors, come out to plaaaaaaeeeeaaaaaay”.
See Sean Penn's full filmography, biographical information, awards and nominations and more on IMDb.com.
To see The Warriors full cast and crew, click here.