A supporting character in the original 1979 Phantasm, Reggie Bannister’s character of ice cream vendor Reggie was created (along with the other characters) for “single use”. When the sequel rolled around in 1988, Don Coscarelli reconfigured both Michael and Reggie to fit in a more franchise-friendly narrative. The Reggie as we know him - all-action, persevering, lady-loving - wasn’t really born until Phantasm 2.
Like another 80’s-forged character who was resourceful with everday objects - TV’s MacGyver* - Reggie’s full name has never been revealed (I know what it is, but I’ll never tell). Makes you wish we had gotten a close-up of his driver’s license when an incognito demon Officer Bob Ivy pulled him over. The roots of Reggie’s single name are in the 70’s creation of Phantasm - with Bannister as the real-life template of an easygoing friend, Coscarelli devised the character to share the same first name because he was just like him. Just some good guy. “Just Reggie” - an archetypal reliable friend. *And yes smarty pants, I know MacGyver’s first name was revealed to be Angus, but that was in the final season, 1992.
The notion of “Just Reggie” gained additional impact when he stepped up to the plate to help drive the story (and cuda - Phantasm 2). In its era, singular-named action stars as well as characters (like Schwarzenegger, Rambo) were big hits with audiences. Many grew up watching those flicks and its that nostalgia that placed Reggie and his real-life alter-ego on the road to cultdom - and subsequently welcomed with open arms larger role in Phantasm 3.
There’s no way to put it milder - Reggie is akin to an Arthurian Knight. He’s trained in arms, and has certainly proved himself chivalrous with the ladies - even if his intentions are more lust than love. Witness his gentlemanly manners throughout his encounters with pre-demonic Alchemy (Phantasm 2) and Jennifer (Phantasm 4). It’s perhaps ironic that he was the least romantic with Rocky (Phantasm 3), the only one of his gals who later turned out to be - shock - an actual human being.
The rules of Phantasmverse are… there are no rules. There is only an accepted truth that anything can happen at any time. But its interesting that they’ve never called Reggie’s character into question. Like a nexus of reality at the center of chaos (”If you can keep your head when all about you are losing theirs…”) Reggie has been the one constant that Michael - and the audience - could count on to balance off the unreality. It’s likely for that reason that Coscarelli has always kept Reggie grounded and free of supernatural/sci-fi shenanigans. Don’t expect Reggie to be revealed as a dwarf on stilts anytime soon.
Dimensions are added (no pun…) to Reggie through character flaws - he’s easily led by ‘Lil Reg, and is too reliant on firepower when it’s never proved to halt the overall threat. It’s only bought him more time. It should be noted that Reggie tends to smarten up as the series progresses - he becomes more wary of mental threats like Jody’s Apparition, and handing Michael the tuning fork (Phantasm 4) was such an old-school and thoughtful solution, one spinning directly out of his musical past (Phantasm) and completely unrelated to B.S.U. (Blowing S**t Up).
Lastly, consider Michael’s earlier mental institution situation (Phantasm 2). Everyone around him in his immediate life, people that would have known him for years, would have labeled him crazy. Turned their backs on him. But Reggie stuck by him regardless for all that time. He may not have believed in Michael’s tall tales but he believed in Michael. Friends like that are few and far between - especially in Film/TV these days as cynical back-stabby types have become the norm. There’s something undeniably heartwarming and appealing about the character of Reggie.