Twilight's 2008 adaptation added a seemingly pointless minor character to the plot, but there is a reason that Waylon Forge appears in the movie and not in the source novel. The Twilight Saga was a box office success thanks to the massive existing fan base of Stephenie Meyer's best-selling books. Since Twilight fans were avid admirers of Meyer's work, there was a lot of pressure on the Twilight movies to be faithful to her books.
In some cases, this resulted in positive creative outcomes, like Paramount canceling a comically misguided Twilight adaptation that would have involved a gun-toting Bella and vampiric villains on jet skis. In other instances, it led to issues like Twilight director Catherine Hardwicke not getting the diverse cast she wanted for the original movie because Meyer vetoed her choices. However, Hardwicke's original Twilight did get to make one important change to the source material.
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While Twilight's disappointingly tame vampires don't rack up much of a body count across the saga, the villains of the original movie do kill one unfortunate Forks local early on in the action. The character of Waylon Forge doesn't appear in the source novel Twilight, but he has two scenes in the otherwise largely faithful movie adaptation. In one, the good-natured Waylon (played by Ned Bellamy) asks Bella (Kristen Stewart) whether she remembers him playing Santa Claus during her childhood. In the second, he is accosted and killed by the villainous vampire coven plaguing the town. While these scenes aren't very long, they are both vital additions to Twilight's plot.
Waylon Forge was added to the cast so that he could be killed off, thus proving that Victoria, James, and Laurent's movie incarnations were more threatening than their book counterparts. Unlike True Blood's R-rated bloodsuckers, Twilight's vampires killed barely anyone in the original movie, with the Cullen clan surviving by draining animal blood. The original Meyer novel was even more bloodless, with Edward killing James in self-defense at the end of the book but no one else dying despite the dark romance's supernatural elements. Catherine Hardwicke's Twilight movie adaptation improved on this by adding an early murder that made the villains seem more dangerous and the movie more mature and darker as a result.
While Waylon didn't have much to do during his brief screen time, his short appearance did mark him out as a sweet, well-meaning local, a long-time friend of Bella's father, Charlie, and an acquaintance of the movie's heroine. He wasn't a major Twilight Saga character, but he was clearly a good guy, making Twilight's murder mystery subplot a dark addition that gave the plot more tension. Thus, Waylon Forge was a valuable addition to the story of Twilight, even if his minor role didn't extend past him being killed off early in the movie's action.