 | Tommy Lee Jones | .... | Kevin Brown, Agent Kay |
 | Will Smith | .... | Agent Jay |
 | Rip Torn | .... | Zed |
 | Lara Flynn Boyle | .... | Serleena |
 | Johnny Knoxville | .... | Scrad / Charlie |
 | Rosario Dawson | .... | Laura Vasquez |
 | Tony Shalhoub | .... | Jack Jeebs |
 | Patrick Warburton | .... | Agent T |
 | Jack Kehler | .... | Ben |
 | David Cross | .... | Newton |
 | Colombe Jacobsen | .... | Hailey |
 | Peter Spellos | .... | Captain Larry Bridgewater, The Motorman |
 | Michael Rivkin | .... | Man with Harvey, the Dog |
 | Michael Bailey Smith | .... | Creepy |
 | Lenny Venito | .... | New York Guy |
 | Howard Spiegel | .... | New York Guy |
 | Alpheus Merchant | .... | MIB Guard |
 | Jay Johnston | .... | Younger Pizza Parlor MIB Agent |
 | Joel McKinnon Miller | .... | Agent |
 | Derek Cecil | .... | Repairman Agent |
 | Sean Rouse | .... | MIB Agent |
 | Peter Spruyt | .... | MIB Customs Agent |
 | Kevin Cotteleer | .... | MIB Customs Agent |
 | Marty Belafsky | .... | MIB Customs Agent |
 | Rick Baker | .... | MIB Passport Control Agent |
 | Martha Stewart | .... | Herself |
 | Michael Jackson | .... | Agent M |
 | Sid Garza-Hillman | .... | Agent Gee |
 | Tom Whitenight | .... | MIB Agent C |
 | Nick Cannon | .... | MIB Autopsy Agent |
 | Andre Blair | .... | Central Park Agent |
 | Jeremy Howard | .... | Bird Guy Alien / Postal Sorting Alien |
 | Mary Stein | .... | Bird Lady Alien |
 | Marty Klebba | .... | Family Child Alien |
 | John Alexander | .... | Jarra / Family Dad Alien |
 | Denise Cheshire | .... | Family Mom / Locker Alien |
 | Ernie Grunwald | .... | Young Postal Employee |
 | Chloe Sonnenfeld | .... | Elizabeth, Young Girl at the Post Office |
 | John Berton | .... | Split Alien Guy |
 | William E. Jackson | .... | Eye Guy |
 | Doug Jones | .... | Joey |
 | Biz Markie | .... | Rapping Alien |
 | Peter Graves | .... | Himself |
 | Linda Kim | .... | Ambassador Lauranna |
 | Paige Brooks | .... | 'Mysteries in History' Lauranna |
 | Stephanie Kemp | .... | Neuralyzed Mother |
 | Barry Sonnenfeld | .... | Neuralyzed Father |
 | Victoria Jones | .... | Neuralyzed Daughter |
 | Michael Garvey | .... | Corn Face |
 | Michael Dahlen | .... | Flesh Balls |
 | Kevin Grevioux | .... | Pineal Eye |
 | Derek Mears | .... | Mosh Tendrils |
 | Sonny Tipton | .... | Dog Poop |
 | John Richardson | .... | Postman |
 | Philip Goodwin | .... | Diner Guy |
 | Tim Blaney | .... | Frank the Pug (voice) |
 | Greg Ballora | .... | Sleeble (voice) |
 | Carl J. Johnson | .... | Gleeble (voice) |
 | Thom Fountain | .... | Neeble (voice) |
 | Brad Abrell | .... | Mannix (voice) |
 | Richard Pearson | .... | Gordy (voice) |
 | John D. Bair | .... | Alien Attack Victim (uncredited) |
 | Michael Beardsley | .... | Suspicious Video Store Patron (uncredited) |
 | Michael Buonomo | .... | College Student (uncredited) |
 | Kristin Charney | .... | Family Mom (uncredited) |
 | Patrick Coleman Duncan | .... | 'History's Mysteries' Alien (uncredited) |
 | Darrell Foster | .... | MIB Autopsy Agent (uncredited) |
 | Ned Gorman | .... | Cockroach on Sidewalk (uncredited, voice) |
 | William Jackson Jr. | .... | Eye Guy (uncredited) |
 | Gene LeBell | .... | Subway Passenger (uncredited) |
 | Pete Macnamara | .... | Man in Black (uncredited) |
 | Jon M. McDonnell | .... | Man in Street (uncredited) |
 | Matthew McGrory | .... | Tall Alien (uncredited) |
 | Christopher Metas | .... | Alien Accountant (uncredited) |
 | Nikki Milican Bedwell | .... | Agent (uncredited) |
 | Bart Mixon | .... | Alien Puppeteer (uncredited) |
 | David Patykewich | .... | Bald Kid Alien (uncredited) |
 | David C. Roehm Sr. | .... | Alien (uncredited) |
 | Thomas Rosales, jr. | .... | Subway Passenger (uncredited) |
 | Hannah Sim | .... | Head-Bobbing Alien (uncredited) |
 | Peter Siragusa | .... | Mayor of Grand Central Station Locker Al (uncredited, voice) |
 | Daniel Browning Smith | .... | Aquarium Boy (uncredited) |
 | Brian Steele | .... | Sharkmouth (uncredited) |
 | Mark Steger | .... | Quadraped Alien (uncredited) |
 | Alan Tuskes | .... | Lobsterhead Alien (uncredited) |
 | Shannon Watson | .... | 70's MIB agent (uncredited) |
 | David K. Zandi | .... | Alien (uncredited) |