Men in Black III (2012) ALL
After breaking out of a moon-based maximum security prison, Boris the Animal decides to go back in time and eliminate the person who arrested him - Agent K. When he does so, Agent J realizes that the time line has been changed and he too travels back to July 15, 1969, the day before Agent K is killed. After overcoming some disbelief, J manages to convince K and others of just who he is and why he's there. With the help of a being who can see all time lines, they track Boris down. J also learns a secret, something K had never told him.
When an alien confined to a penal colony in space escapes, he goes to Earth to get the man who placed him there, MIB agent K. He confronts K, K and J corner him but he disappears. The next day J goes to pick up K but finds someone else living at his apartment. When he goes to MIB; he looks for K but everyone there tells him. K died in 1969 after tackling the alien. But J says K captured him. That's when alien vessels which are from the planet of the alien whom K and J encountered and they're about to destroy the Earth. But J says that K placed a barrier that keeps them from entering Earth. It's obvious the alien went back in time and killed K before he could deploy the barrier. So J goes to sees an alien on Earth whose father was also at the penal colony, whom J assumes told the alien that he worked on time travel and his son has the device. J goes to see him and tells him about the invasion. So he sends J back just before K's death. J arrives in 1969 and fails to stop the alien and is captured by the younger K and J was told not to tell him anything. But with time running out J tells him but K doesn't believe him at first, so they go out to stop the alien. Only problem J doesn't exactly know what he is doing in 1969.
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.