Rex Dangervest

"Only the toughest can get out of there alive!"

- Rex's most famous line.

Rex Dangervest is the main antagonist of the 2019 animated film The LEGO Movie 2: The Second Part. He is a galaxy-defending archaeologist, cowboy and raptor trainer and while at first appearing as an ally of Emmet Brickowski, he reveals himself to be an embittered future Emmet who, after crashing and being thought dead by his friends, became resentful upon seeing them move on without him and built a time machine so he could travel back in time and cause the "our-mom-ageddon" as revenge.

He was voiced by Chris Pratt, who also played Fletcher Flemson in Bride Wars.

History
While he was still Emmet Brickowski, Rex crashed his spaceship into an asteroid field and wound up behind a clothes dryer in the real world. After seeing all his friends continue to go on after his supposed death, Rex became resentful towards them and built a time machine so he could travel back in time and ensure the "our-mom-ageddon" occurred.

Rex saved Emmet as he was about to crash into an asteroid field and teamed up with his past self to venture to the Systar System and save his friends from the DUPLO Aliens. As they continue on to the Systar system, Emmet begins to take on several of Rex's mannerism, hoping to impress Lucy. When they arrive, they evade capture by Wa'Nabi's forces by swamp creatures and "brainwashed" of most of the people by singing Cathy Song.

Outside, Emmet is reunited with Lucy and they embrace, but no so much when she meets Rex. Rex tells Emmet has managed to have his own habilites and force by making him tough. Despite Emmet's joy of this by impressing her, Lucy is sort of dissopinted by this. Once they escape for the Duplo Brickyard, they make up a plan which involves switching off the pop music that is brainwashing the others, while Emmet will destroy the reception cake encased in a temple to stop the wedding between Batman and Wanabi. However, Rex and Emmet are shocked when Lucy reviels her original hair to them, and she affirms it's her real hair and that she was not brainwashed. Despite Rex warnings, Emmet believes is the real Lucy since she knows her for a long time, and she helps them to the plan.

Despite Lucy warns after she knows the real intentions of the DUPLO people, Emmet destroys the reception cake at the wedding between Batman and the Queen of the DUPLO Aliens, Watevra Wa'Nabi. Emmet soon realizes after learning that the DUPLO Aliens only wanted peace between themselves and Bricksburg and seeing a hole in the universe appear in wake of the cake's destruction. The cake being destroyed is mirrored in the real world by Finn angrily destroying Bianca's Lego creations, causing their mother to scold them and tell them to put their toys away. Emmet tries to stop them but is prevented by Rex revealing his true colors as Emmett's future self and reveals that he traveled back in time to ensure the "our-mom-ageddon" would happen. When the two fight and Rex knocks Emmett under the dryer so that he will continue to exist. However, determined to not become like Rex, Emmet is returned into the Lego world when Lucy arrives in front of him and Rex and they both embrace.

Rex thinks they are too late and attempts to go back in time, but Lucy manages to trick Rex into punching a cute sentient heart, triggering an explosion, destroying his time machine and Rex topples in defeat. Lucy then tells Rex that Emmet will not become like him, erasing his timeline and causing the deluded time-traveler to begin disappearing. As he fades away, Rex realizes that Emmet being saved by Lucy means he didn't ended up becoming him and tells Emmet to always be upbeat, says his last words: "Besides, this is a pretty righteous way to go out, no regrets! Except again not trademarking "No regrets", that was a mistake, regrets!" before fading completely from existence.

Trivia

 * Queen Whatevera Wanabi and General Sweet Mayhem were marketed as the main antagonists of The LEGO Movie 2: The Second Part. The twist reveal that Rex would be the true main antagonist was hidden in all promotional and marketing material.
 * Rex's occupations are references to past roles that his voice actor, Chris Pratt, has played in his acting career.
 * Archaeologist; a reference to a rumor that Chris Pratt would portray Indiana Jones in a reboot.
 * Cowboy; a reference to Joshua Faraday in The Magnificent Seven.
 * Galaxy Defender; a reference to Peter Quill/Star-Lord in the Marvel Cinematic Universe.
 * Additionally, Rex makes a reference to how he has a chiseled jawline hidden under baby fat. This is more likely than not a reference to Chris Pratt's career prior to his breakthrough in 2014, where he was significantly overweight. He lost this weight while undergoing intense training for his role as Peter Quill/Star-Lord in Guardians of the Galaxy.
 * Raptor Trainer; a reference to Owen Grady in Jurassic World and Jurassic World: Fallen Kingdom.
 * He is the first and so-far the only villain in The LEGO Movie franchise to ever die, as far as the LEGO universe narrative is concerned (taking in mind that the film's events in regard to Rex's time-travel twist was all in Finn's head).