Cast
Credited cast:
  Will Smith  ...  Agent J 
  Tim Burton   
  Alice Eve  ...  Young Agent O 
  Josh Brolin  ...  Young Agent K 
  Justin Bieber   
  Tommy Lee Jones  ...  Agent K 
  Emma Thompson  ...  O 
  Bill Hader  ...  Andy Warhol 
  Lady Gaga   
  Jemaine Clement  ...  Boris 
  Nicole Scherzinger  ...  Lilly 
  Michael Stuhlbarg  ...  Griffin 
  Yuri Lowenthal  ...  Knuckles (voice) 
  Kevin Covais  ...  MIB Agent #5 - Intern 
  Joseph R. Gannascoli  ...  Mets Fan 

An alien criminal kills the young Agent K in 1969, altering the timeline, changing the Agency and placing the Earth in danger. Veteran Agent J (Will Smith) must travel back in time to 1969 to before the murder and work with the young Agent K (Josh Brolin) to save him, the Agency, the Earth and humanity itself.

The film's premise was first proposed to director Barry Sonnenfeld by Will Smith during the filming of Men in Black II in 2002, with Smith suggesting that his character, Agent J, travel back in time to save his partner, Agent K, and while at the same time exploring Agent K's backstory. Sonnenfeld said the idea "turned out to be a very long process of development, mainly because of the knotting [sic] issues of time travel...."^[17] The film was first announced on April 1, 2009, by Sony Pictures Entertainment president Rory Bruer during a Sony ShoWest presentation.^[18] By October 2009, Etan Cohen had been hired to write the screenplay.^[19] As of March 2010, Will Smith remained undecided whether to join this film or another, The City That Sailed.^[20] Director Barry Sonnenfeld in May 2010 confirmed the return of the protagonists played by Tommy Lee Jones and Smith.^[7] Both had expressed interest in 2008 in reprising their roles.^[21][22] Other staff includes Walter F. Parkes and Laurie MacDonald as producers, with Steven Spielberg as executive producer; all were producers of the two previous films.^[23]

In June, writer David Koepp was hired to rewrite the Cohen script.^[24] On June 11, 2010, the fan site SonyInsider.com posted what it described as a "clip [that] debuted at an exclusive Sony 3D TV launch event at Sony Pictures Studios",^[25] showing Smith dressed as Agent J wearing 3-D glasses and stating, "I know what you're thinking — 'M.I.B.', 3-D, we're going to be blowing stuff up and all that. But that's not really what we're doing right now. We're here for one purpose, and for one purpose only: Just to let you know that I'm about to make 3-D look good."^[26] A teaser poster for the film was also released on September 21, 2010.^[27] A third writer, Jeff Nathanson, was hired in November 2010 to rewrite the time-travel segment of the script in which the story takes place in 1969.^[28] Nathanson and Koepp, along with producer Spielberg, had previously worked together on the 2008 film Indiana Jones and the Kingdom of the Crystal Skull.

Principal photography began on November 16, 2010.^[29] even though, "We knew starting the movie that we didn't have a finished second or third act," director Sonnenfeld said in 2012. "Was it responsible? The answer is, if this movie does as well as I think it will, it was genius. If it's a total failure, then it was a really stupid idea."^[30] It was originally slated to commence on October 18, 2010, and continue until May 2011 in New York City,^[31] with shooting starting in 2010 partly in order to take advantage of a New York tax break in which the state rebates 30 percent of production costs incurred there.^[3] Filming was split into two parts, the first taking place from November until about Christmas 2010; the filmmakers announced shooting would begin again in mid-February, but it was delayed until April.^[3]

The first set photos for the film turned up online on November 17, 2010 showing Will Smith, Tommy Lee Jones, Emma Thompson, and Nicole Scherzinger on set.^[32] Shooting was scheduled to resume from March through June 2011.^[33] Filming was done in April 2011 in the Morris Park section of The Bronx.^[34] Parts of Coney Island, in Brooklyn, had parking and filming permits posted for April 24 and May 2-4, 2011, production dates of what the permits titled MIB³.^[35]