Featuring the voices of Reese Witherspoon, Seth Rogen, Hugh Laurie, Will Arnett, Kiefer Sutherland, Rainn Wilson, Paul Rudd, and Stephen Colbert, the film involves a group of misfit monsters hired by the United States Armed Forces to stop the invasion of an extraterrestrial villain and save the world in exchange for freedom.

Though she initially appears unharmed, during the ceremony, the energy causes Susan to grow fifty feet tall, accidentally destroying the church in the process.

(Benzoate Ostylezene Bicarbonate), a brainless and living indestructible mass of blue goo that is a result of a food flavoring mutation; the Missing Link, a prehistoric 20,000-year-old fish-ape hybrid who was thawed from deep ice by scientists; and Insectosaurus, a massive bug mutated by nuclear radiation standing 350 feet in height that attacked Tokyo.

Meanwhile, on a mysterious spaceship, a squid-like extraterrestrial overlord named Gallaxhar is alerted to the presence of a powerful substance known as "Quantonium", and sends a gigantic robotic probe to retrieve it.

Onboard the ship, Ginormica furiously breaks free from her prison cell and chases down Gallaxhar, only to be trapped by a machine that extracts the Quantonium from her body, shrinking her back to her original size.

Monger then arrives to inform the monsters that a monstrous snail named "Escargantua" is slowly making its way to Paris after falling into a nuclear reactor, resulting in the heroes taking off to confront the new menace.

[14] In a plot synopsis revealed in 2005, Rex was to assemble a team of monsters, including Ick!, Dr. Cockroach, the 50,000 Pound Woman and Insectosaurus, to fight aliens for disrupting cable TV service.

[12] In the following years, the film's story diverged away from the original Rex Havoc, with directors Conrad Vernon and Rob Letterman finally creating the storyline from scratch.

[15] Production designer David James stated that the film is "a return to what made us nerds in the first place," getting classic movie monsters and relaunching them in a contemporary setting.

Director Conrad Vernon added that he found it would be a great idea to take hideous monsters and give them personalities and satirize the archetypes.

[16] Ed Leonard, CTO of DreamWorks Animation, says it took approximately 45.6 million computing hours to make Monsters vs. Aliens, more than eight times as many as the original Shrek.

[18] Starting with Monsters vs. Aliens, all feature films released by DreamWorks Animation were produced in a stereoscopic 3D format, using Intel's InTru3D technology.

To promote the 3D technology that is used in Monsters vs. Aliens, DreamWorks ran a 3D trailer before halftime in the U.S. broadcast of Super Bowl XLIII on February 1, 2009.

Due to the limitations of television technology at the time, ColorCode 3-D glasses were distributed at SoBe stands at major national grocers.

[22] On February 24, a tentative March release date was set for the United Kingdom, where anyone who buys a Samsung 3D TV or 3D Blu-ray player will get a copy.

The critical consensus reads: "Though it doesn't approach the depth of the best-animated films, Monsters vs. Aliens has enough humor and special effects to entertain moviegoers of all ages.

[32] Roger Ebert of the Chicago Sun-Times gave the film two and a half stars out of four, writing, "I suppose kids will like this movie", though he "didn't find [it] rich with humor".