O/T....Best acting in a movie

In order for me to consider a specific performance among my favorites, I have to forget that I'm watching the actor - the character they're playing, whoever it is, I need to believe it. Meaning, I enjoy Tom Cruise movies, but I'm always aware that I'm watching Tom Cruise. With that being said, here are a few of my favorite individual performances.

Gabriel Byre in The Usual Suspects (the entire cast really, but mainly him)
Viggo Mortensen in G.I. Jane
Gene Hackman in Hoosiers
Robin Williams in Good Will Hunting
Fred Ward in Tremors
Samuel L. Jackson in Pulp Fiction
Jeff Bridges in The Fabulous Baker Boys
Leonardo DiCaprio in Blood Diamond
Daniel Day Lewis in Gangs of New York
Ed Harris in The Abyss
Michael Douglas in The Game
Kevin Kline in Dave
Clint Eastwood in In The Line Of Fire
Harvey Keitel in Reservoir Dogs

Sigourney Weaver in Aliens
Kate Winslet in Revolutionary Road
Meryl Streep in...hard to pick just one, I guess Kramer vs. Kramer or Silkwood
Marisa Tomei in My Cousin Vinny
Cher in Mask
Julianne Moore in Still Alice
Nicole Kidman in The Others
Jodi Foster in Silence of the Lambs
Susan Sarandon in Thelma & Louise
Michelle Pfeiffer in The Fabulous Baker Boys

To name a few.