Sinopsis
La película comienza con la fuga de un extraño y poderoso extraterrestre llamado Boris el animal. Es el último superviviente de la raza alienígena boglodita, que sobrevive mediante el ataque, toma, y ocupación de otros planetas habitados. Boris es un asesino, que fue capturado por el agente K y encarcelado en una prisión secreta en la Luna. K también pudo desplegar un sistema de defensa (denominado "Arca Net"), y evitar una invasión boglodita, logrando así su extinción. Sin embargo, Boris logra burlar la seguridad y destruir gran parte de la cárcel, para escapar y vengarse de K.
Reparto
Will Smith — Agent JTommy Lee Jones — Agent KJosh Brolin — Young Agent KJemaine Clement — Boris The AnimalEmma Thompson — Agent OMichael Stuhlbarg — GriffinMike Colter — ColonelNicole Scherzinger — Boris's GirlfriendMichael Chernus — Jeffrey PriceAlice Eve — Young Agent ODavid Rasche — Agent XKeone Young — Mr. WuBill Hader — Andy WarholCayen Martin — Colonel's SonClarke Thorell — Prison Guard #1Adam Mucci — Prison Guard #2Tom McComas — Prison Guard #3Douglas Crosby — Prison Guard #4Woodie King Jr. — 2012 MIB HQ GuardJack O'Connell — 1969 MIB HQ GuardTobias Segal — 1969 MIB Agent #1Jon Shaver — 1969 MIB Agent #2Gerritt Vandermeer — 1969 MIB Agent #3Alexandra O'Hara — MomViolet O'Hara — Little Chocolate Milk GirlValence Thomas — Coney Island HippieChloe Sonnenfeld — Coney Island Flower ChildLanny Flaherty — Obadiah PriceJonathan O'Hara — MIB Desk AgentRick Baker — Brain AlienJoseph D'Onofrio — New York Mets Fan #1Joseph R. Gannascoli — New York Mets Fan #2Katy Frame — Diner WaitressKevin Townley — Funky 60's DudeStephen Brian Jones — GuruTyler Johnson — Muscle Boy at HappeningKati Rediger — Muscle Boy's Girlfriend at HappeningVictor Joel Ortiz — Air Force MP #1Charlie Barnett — Air Force MP #2Ian Blackman — Car Theft VictimJeremy Beiler — Hotel DoormanLiliane Klein — Screaming Lady on Ferris WheelBritt Chandler Johnson — Detained Teenage AlienJared Johnston — Neil ArmstrongKen Arnold — Buzz AldrinJonathan Drew — Michael CollinsJoel Brady — 1969 Man in ElevatorDavid Pittu — Roman The FabulistLenny Venito — Bowling Ball HeadAnthony J. Gallo — Four-Armed AlienJames Martin Kelly — 1969 NYPD Cop #1Will McLaughlin — 1969 NYPD Cop #2Kimmy Suzuki — Mr. Wu's BartenderKirk Larsen — Dead ZedRebecca Glasscock — Transvestite at HappeningBarry Sonnenfeld — Husband Watching LaunchSusan Ringo — Wife Watching LaunchStephanie Ellis — Young Wife #1 Watching LaunchBen Mac Brown — Young Husband #1 Watching LaunchAmy Erwitt — Young Wife #2 Watching LaunchBrad Abrell — Worm (voice)Tim Blaney — Worm (voice)Thom Fountain — Worm (voice)Carl J. Johnson — Worm (voice)Will Arnett — Agent AA (uncredited)Jada Pinkett Smith — Party Guest (uncredited)Tony Shalhoub — 1969 Newsstand Vendor (uncredited)Alex Ziwak — Prisoner (uncredited)Jason Liles — Feelers / Colussus (uncredited)Jesse Ridgway — Pedestrian (uncredited)Justin Bieber — Alien on TV Monitors (uncredited)Erin Lindsey Krom — Headquarters Secretary (uncredited)Tim Burton — Alien on TV Monitors (uncredited)Eha Urbsalu — 1969 MIB Secretary #1 (uncredited)Rip Torn — Large-Headed Alien at Funeral (uncredited)Howard Stern — 1969 Man in MIB HQ (uncredited)Alpheus Merchant — MIB Guard (uncredited)Leonard Zimmerman — Warhol Benefactor (uncredited)Liz Logan — Coney Island Sunbather (uncredited)