Madison Square Garden was packed last night with Lady Gaga's "Little Monsters" -- and some of them had some famous faces!
Michelle Pfeiffer, her husband David E. Kelly, Green Day's Billie Joe Armstrong and ice skater Johnny Weir all attended the pop star's big show last night in NYC -- which was filmed for an upcoming HBO special, airing May 7.
Check out Gaga's celeb fans above -- plus shots of the wild outfits her other "monsters" wore to the show!
