Halloween Kills saw the return of many well-known characters to the franchise, including Dr. Sam Loomis, though his cameo was a big mistake on the part of the movie. The character was a major player in John Carpenter’s original Halloween, played by the late respected British actor Donald Pleasence. The actor brought a dignified gravity to the iconic horror film as Michael Myers’ psychiatrist who seeks to track the killer down when he escapes incarceration. Loomis has been featured in eight of the twelve Halloween films, tying with Laurie Strode (Jamie Lee Curtis) for the second-most number of appearances in the franchise behind Michael himself.
Dr. Loomis makes a couple of brief appearances in Halloween Kills when the movie flashes back to previously unseen events on the night of Michael’s initial killing spree in 1978. Dr. Loomis gets a new actor for Halloween Kills, played by the film’s art director, Tom Jones, Jr., impressively utilizing prosthetics and clever lighting to more closely imitate the late Pleasance’s appearance, with Colin Mahan providing vocal performance for the character. Loomis is revealed to have nearly killed Michael after his arrest in 1978 before being stopped by a then-young Deputy Frank Hawkins (played Thomas Mann in the flashbacks).
While Loomis’ cameo may have been exciting for a few of the franchise's devotees, his appearance doesn’t otherwise add much to the film. Critics have already pointed out that Halloween Kills has a weak plot, using Michael’s increasingly violent activity to distract from poor dialogue and character development. But Loomis’ role in the film highlights more bad storytelling choices made in the middle film of director David Gordon Green’s reboot trilogy. Loomis does relatively little in this film, only appearing to ask Hawkins if Michael had killed again and then to make an attempt at killing the murderer. The movie sees the fruition of Loomis' worst fear so it's not unbelievable for Loomis to do such things, but Halloween Kills would not have lost any story momentum if these actions had been taken by Hawkins or removed at all. Shoehorning Loomis in ends up feeling like a piece of blatant fan service rather than an appearance that actually has an impact on the story.
Dr. Loomis is a character firmly planted in the past of Haddonfield, IL, the town in which the events of both the original Halloween and Green's sequels take place. While the focus on the 2018 Halloween explored the impact that Myers' past actions have had on Laurie in the present, Halloween Kills expands that exploration to Michael's impact on the whole of Haddonfield, with a couple of retcons. The biggest problem with this angle is that it's about characters who have had little development over past films in the series.
Because of the weak character and plot development occurring in Haddonfield's present, the filmmakers turn to the past. The doctor's appearance is meant both to distract audiences from the lack of development and to be a substitute for the lack of compelling characters, since most are at least familiar with Dr. Loomis despite Halloween Kills' change of timeline. The return of the doctor is certainly surprising, and the physical likeness is very well done in comparison to poor reconstructions of characters previously played by aged or deceased actors in other franchises. Hardcore followers of the franchise may be briefly amused by Loomis' role in Halloween Kills but rather than pointing away the insufficiencies of the plot, it actually directs viewers to the film's biggest failures.