Known in Grover's Bend as the town drunk, Charlie believes in the existence of extraterrestrials and frequently claims to be in contact with them via his teeth or headaches. He works with Jay Brown on his vehicles at the Brown farm, where he talks with his one and only friend, Brad Brown. He accidentally shoots April Brown with Brad's slingshot, and Brad is punished for it. On the way home that night, Charlie witnesses the Crite ship in the sky, and cycles back to town in a panic, pleading with Sal to call the army, although his ramblings are dismissed as being drunk.
He goes to the town's bowling alley for a drink, but his suspicions are confirmed when the Bounty Hunters appear and mimic Charlie's appearance, freaking him out. He then follows them back to the Brown farm, where the Crites are just getting ready to leave. He helps Brad get April out of the ship, and lights his bottle of whiskey as a molotov cocktail and throws it through the ship's door, igniting Brad's firecracker and destroying the ship.
As the Bounty Hunters leave, Charlie is seen following them, asking for a Communicator like the one they gave to Brad. In Critters 2, it is revealed the Bounty Hunters took Charlie with them to become a Bounty Hunter himself.
Returning to Earth following a report from the Intergalactic Council that Earth is host to residual Crite life, Charlie is reunited with Brad Brown in Grover's Bend, along with Ug and Lee (the two Bounty Hunters). He explains to Brad that his life is now in space with them, since he was a nobody on Earth. He also explains that he has given up drinking, as he doesn't need it any longer.
Charlie helps with the fight against the Crites for the majority of the film, but when Lee is killed, Ug reverts back to his blank alien appearance. Charlie pleads with Ug to try and transform again, since he feel incapable of fighting the Crites alone. He eventually assists Brad in his plan to trap the Crites in a frozen food factory, but flees when the Crites show signs of returning back towards the citizens of Grover's Bend.
When the factory explodes, and the Crite ball emerges, Brad and Megan crash their truck trying to ram it off the road. When all hope seems lost, Charlie pilots his spacecraft and crashes it into the Crite ball, destroying the ship and the Crites. Seemingly dead, he turns up at the film's climax to say goodbye to Brad as he leaves Grover's Bend. Ug also bids farewell, as he feels Charlie is now ready to remain on Earth. With that, Sheriff Harv then tosses Charlie his sheriff badge, making Charlie the new sheriff of Grover's Bend.
Although unexplained, it is revealed that one stray Crite has survived the second film's events and Charlie is encountered by Annie, Josh and Johnny at the film's beginning, hunting the last one down. He explains the events that happened in the first two films to them, and warns them that he only has one left. He also gives Johnny a crystal that glows green when it detects Crites nearby, before leaving to search.
He is not seen again until the Crites have attacked the tenement building that Annie lives in. Mr. Menges had called him to ask him questions about the Crites when Johnny's crystal starts glowing green, and Charlie had made it to the building, just in time to save Annie from several Crites. He reunites with the survivors, and shoots a Crite that attacks them, leaving an entry to the roof. On the roof, Charlie dives in front of Johnny to save him from a Crite attack, and ends up hanging onto a pole dangling off the building. It doesn't last long and Charlie collides with Cliff's van, eventually discovering the dead Crite speared on an aerial.
He bids farewell to the survivors and searches the building's burnt basement level, in search of stray Crites. He finds only two eggs remaining, and then suddenly, his Communicator rings out loudly, warning him that he is in violation. A hologram of Ug appears and explains that under Intergalactic law, he cannot destroy the last two eggs as that would render the Crites extinct. Ug tells Charlie a specimen collection pod has been dispatched to send the eggs back to the Council, and that he is tasked with putting them in there. The film ends just as the pod bursts through the roof.
Picking up exactly where Critters 3 left off, Charlie puts the Crite eggs into coffee cans and gets into the pod, placing them into their receptacles. The door closes on him, and he is unable to escape the pod before it puts Charlie and the Crite eggs into a deep hypersleep.
53 years later, the pod is encountered by the R.S.S Tesla, a salvage craft, who capture the pod and are contacted by Ug (now a businessman named Counselor Tetra). The crew travel to the nearest TeraCor space station, and the greedy captain, Rick, decides to breach the pod despite Tetra's instructions. He manages to open the pod's door, while Charlie wakes up and in a panic, exits the pod, bumping into Rick. Deciding to investigate, Rick enters the pod and discovers the coffee cans, now containing broken Crite eggs. The two baby Crites attack Rick, with one viciously jumping into his mouth and eating his tongue and gums. Charlie tries to shoot them but his gun falls apart, so as the Crites finish off Rick, Charlie grabs Rick's laser gun and fires, only singeing the head of one of them. The Crites roll away, and Charlie befriends a comatose Ethan, who had been knocked out by Rick earlier.
The pair make their way through an abandoned lab and accidentally fall into the ship's garbage refuse system. After narrowly escaping decompression, Charlie tries to explain his story to Ethan, Fran, Bernie and Al Bert, but they are dismissive of it, since Charlie still believes he is in the year 1992. He faints after hearing what year it actually is.
He wakes up while the crew watch a film about TeraCor's intentions with intergalactic lifeforms, then he becomes nervous when the crew discover Bernie has wandered off alone to the station's pharmacy to steal drugs. He implores Al Bert to call Bernie back when two lifeforms show up on the map scanner, insisting that "It's them!". Bernie however ignores their warnings and is attacked by the Crites and killed. As the crew attempt to leave the space station, they encounter a nest of Crite eggs, so Charlie explains that they take six months to incubate, when an angry Fran tries to crush them.
When they get to the Tesla, a Crite attacks through a vent and Charlie haphazardly shoots at it, and kills it but also destroys the ship's electronics, grounding them at the space station (while the nuclear core begins to melt down). Charlie helps with the repairs, but a TeraCor ship arrives with Ug on it. Charlie is shocked when Ug has seemingly turned traitor and now only cares for retrieving the eggs. He's even further shocked when Ug kills Al Bert with a gun, leaving only him and Fran. Ethan arrives to save them, having disposed of Ug's guards by luring them into a Crite-infested lab. He has the last remaining eggs, and juggles them, throwing them at the walls to antagonise Ug. Ug is eventually shot by Charlie himself, and the three escape in TeraCor's ship while the station is vaporised.
As Ethan and Fran explore the ship, Charlie dons sunglasses and fancies himself a ship captain, and presses a button on the control, which causes the ship to spiral out of control, ending the film.