Lonnie Elam was a sixth grader who bullied Tommy Doyle along with his friends Keith and Richie. On Halloween 1978, Lonnie and his friends were trying to make Tommy believe that the boogeyman was coming after him. He also knew of the story of the Myers house and told his classmates of this. Later that night, Lonnie was dared to enter the Myers house. However, Sam Loomis happened to be hiding behind some bushes. He made a successful attempt to save the children from any danger by scaring them off. Later the same night, Lonnie was hassled by three children from the Mullaney family for apparently stealing their candy. When a policeman drove up to warn them about Michael Myers and tell them to get home, the other children left Lonnie by himself. As Lonnie walked home, he stumbled to the ground and the hulking shape of Michael Myers appeared over him. He looked away in fear and when he turned back, the masked man was gone. As police officers Frank Hawkins and Peter McCabe came to check on him, Lonnie ran away in fear, telling them the Boogeyman will kill them.
In high school, Lonnie was friends with Ray Nelson and occasionally sold him Peyote. Eventually Lonnie and Tommy are able to resolve their differences and become friends because of their shared trauma at seeing Michael Myers that Halloween. Lonnie became obsessed with strange and unusual crimes, visiting the sites of famous murders and paranormal hauntings. Eventually he started writing about his experiences and ended up writing a true crime book about Michael's murders titled The Boogeyman. He also befriends other Myers survivors Lindsey Wallace and Marion Chambers, together they would meet every year at Mike's bar to celebrate their survival and remember Michael's victims.
At some point during the next forty years, Lonnie and his family gain a reputation for being in and out of trouble with the law, one such incident involving his arrest for punching a police officer. Lonnie eventually has a son named Cameron with a woman who left him because of his obsession with death and a tendency to drink too much. Cameron started dating Laurie Strode's granddaughter Allyson. On Halloween 2018, Lonnie sees Cameron and Allyson dressed as Bonnie and Clyde for a party at their school.
40 years later
Later that night, Lonnie goes to the bar with Lindsey, Marion, and Tommy on the night of Halloween 2018, sitting behind Marcus and Vanessa Wilson. Tommy mentions the two homicides at the gas station, Tommy's concerns being brushed off by Lonnie, who tells him that they did not know if Michael was on the bus, and Marion, who refers to Tommy as paranoid. The four laugh and raise their glasses, Marcus requesting that they lower their voices as his wife was trying to watch the talent show. The group complies. Lonnie goes up on stage and begins to introduce Tommy, noting that he used to bully him when they were children but that Tommy was now all-grown up and had "become the most captivating bird whistler." Lonnie leaves the stage and Tommy cames up, greeting the audience with a wave and charging Lonnie with putting him up to coming on stage.
Tommy recounts the story of the "Haddonfield Boogeyman". He introduces Lonnie as having survived a face-to-face encounter. Tommy says that Michael would never get them because they would not succumb to fear and raises his glass in honor of Laurie, Lonnie, Marion, and Lindsey tapping their glasses against each others. Lonnie does not join Tommy, Marion, and Lindsey, instead sitting to himself and watching a puppeteer, laughing to himself as he drinks his glass. Lonnie's phone begins to ring and he puts his glass down to answer it. Knowing that it is Cameron, he addresses him as "Bonnie" and asks if he and "Clyde" need a ride. Cameron explains that he needs him to pick him up and that a police officer was attacked. Becoming serious, Lonnie asks Cameron where he is. Lonnie goes to Tommy, Lindsey, and Marion, telling them that Cameron is in trouble as he quickly rushes out of the bar. Tommy asks him what is wrong.
Lonnie picks Cameron up and takes him to Haddonfield Memorial Hospital, where he finds out that three of Cameron's friends had been murdered earlier that night and that Laurie is being hospitalized for injuries earlier in the night. Tommy arrives at the hospital and Lonnie beats on the hood of his car. Lonnie tells him that they have found Laurie and reports that she is in recovery. Tommy says it is lucky she survived and he reports the findings of the police at Laurie's compound: 11 first responders murdered. Lonnie exclaims an expletive in shock and tells Tommy that Cameron is in the hospital, noting the murders of his friends and calls it a "madhouse." Tommy tells Lonnie that the only way they are going to stop this is if they all come together. Lonnie agrees with Tommy and he directs the latter to the back of his truck, revealing his array of firearms, which Lonnie dubs a "sassy tackle". Tommy asks Lonnie if he has a permit for all of the guns and Lonnie answers, "Some of them."
Cameron runs out of the hospital and calls for his father. Lonnie greets him and asks where his girlfriend is. Cameron tells him that she is okay and is going to stay with her family. Lonnie remarks "Good for her" and Tommy and Cameron exchange greetings before Tommy directs Lonnie to the vehicle pulling up behind them. Lindsey, Vanessa, Marcus, and Marion come out of the car and state their intent to join them in hunting down Michael. Tommy tells Lonnie that they have to give them all protection and that means that he has to share his weapons. Lonnie agrees to do this, and Allyson, who is disobeying instructions to stay at the hospital with her grandmother, comes up to the car and states her interest in joining them. Lonnie tells her to help herself as she looks at his guns.
Lonnie is part of a group with Allyson and Cameron, Allyson screaming out of the back of his truck for people to go inside as it is currently not safe to be out. Allyson turns to Lonnie and asks him if he knew her father. Lonnie confirms this and reflects on the time Ray was freaked out by his own reflection when they were in a canoe together. Lonnie concludes that he will miss Ray as Allyson's laughing turns to crying and Cameron, looking away, calls for his father. Lonnie, thinking that Cameron does not believe his story, asserts that it is true. Cameron explains that he sees Tommy and asks whose car he is standing by. Lonnie identifies it as Lindsey's. Tommy comes up to Lonnie's car, identifies the parked car as Lindsay's, and informs them that the vehicle is covered in blood but that there are no bodies. Tommy tells that them that it is Michael and that he is there, adding that he needs them. As the three exit the vehicle, Tommy warns them to be careful.
Armed with flashlights, Lonnie, Tommy, Allyson, and Cameron call out for Lindsey and Marion. Lonnie spots the corpses of Vanessa and Marcus, whose faces have been covered with masks, and alerts Tommy. Lonnie and Tommy gasp and the pair soon discover Marion's corpse as it is hung up with a mask also covering her face. Tommy identifies her and Lonnie says that Michael did this and exclaims Marion's name in horror. Allyson finds a heavily injured Lindsey laying on the ground and alerts the others to her discovery. The other three come over. As Tommy holds the hysterical Lindsey, who recounts seeing Michael's face, Lonnie proclaims that she is going to be okay as he smiles.
The four take Lindsey out of the park and drive away. As Lindsey is commended by Tommy for standing up to Michael, she reflects on how they used to dare each other to sneak into the Myers house and remembers Lonnie as being the only one brave enough to do it. Lonnie admits that he never made it inside. The group drops Lindsey off at the hospital and Tommy remains there as well in order to protect Laurie, who Karen believes is being targeted by Michael. Lonnie pulls over and shows Allyson and Cameron a map. He concludes that Michael is going home, pointing out that Myers went from Laurie's compound to then murdering people in her neighborhood to the park encounter he had with Lindsey and others earlier. He asserts that tracking those locations makes a straight line, an arrow pointing directly to Lampkin Lane.
Lonnie reflects that he came face-to-face with Michael when he was a kid and notes his pattern of creeping around, killing, and then returning home. Allyson says that then that is where they are going and Lonnie confirms this before driving off. The three arrive in front of the Myers house. Allyson says that the key is to stick together and Lonnie replies that he is going in alone, berating himself for bringing his child to the "belly of the beast." Cameron calls out for his father and Allyson respectfully asks Lonnie if he expects her to sit by while he goes inside to confront the man that murdered her father. Lonnie admits that he does not expect her to, but is asking, for both her sake and Cameron's. Lonnie instructs the two to just stay there and tells them that if they see anything suspicious, honk the horn but warns them to stay safe. 
He takes a gulp of his drink and places his hand on Cameron's shoulder, telling him that he will see him at the finish line. Lonnie exits the car, and with his gun drawn, slowly approaches the front door of the Myers house. He looks back at Allyson and Cameron as they sit in the car, and proceeds. Lonnie peaks into the house through the front door's window and knocks on it to no answer. Lonnie slowly opens the front door and turns around to Allyson and Cameron to signal that everything is okay before he walks inside. Allyson comments about how messed up this is before she and Cameron hear a shot from the inside, the duo exiting the car and entering the Myers house with their weapons to come to Lonnie's aid. Cameron calls for Lonnie and searches the house with Allyson. As the two begin to separate, Cameron notices a closet making a noise. His hand begins having blood drip on it and he loops up, discovering Lonnie's corpse sticking out from the house's attic. This distracts Cameron as Michael begins attacking him in an encounter that would eventually lead to Cameron's death as well.
As a child, Lonnie took delight in tormenting Tommy.
As an adult, Lonnie was not against violating the law, as demonstrated when he showed Tommy his array of firearms and admitted that not all of them had permits when Tommy inquired about the legality of his collection.
Notes and trivia
- Along with Michael, Karen Nelson, Dr. Loomis, Tommy, and Frank Hawkins, Lonnie is one of six characters in this timeline to be played by more than one actor.
- Lonnie, Michael, and Hawkins are the only characters to appear in both the flashback sequence and present story of Halloween Kills.
- Along with Little John, Lonnie is one of two characters that Michael kills off-screen in Halloween Kills.
- Of the four that look for Lindsey in the park, Lonnie is the only one that does not call out her name before she is found.
- After John and Tim Strode in Halloween: The Curse of Michael Myers, Lonnie and Cameron are the second father and son pair that Michael has killed in a single movie.
- Longstreet describes Lonnie as "a complicated, troubled guy who is haunted by his past. Particularly chickening out on going into Michael Myers’ house when he was a kid." Longstreet observed the Elam family as "very unorthodox. They love drugs and alcohol more than most. David said a funny thing to me about that. He said ‘Lonnie knows his wines.’ Ha!!! I don't think I'm a very appropriate father but I love my son.”