Gaston serves as the main antagonist of the original film. He is rude, conceited, small-minded, narcissistic, and spends his time fighting, drinking and hunting. He is considered by many townspeople to be the town hero. Gaston believes that Belle would best suit as his wife based purely on her beauty, but Belle is not as shallow as Gaston and refuses his every advance. His desire to marry Belle leads him to evolve from a narcissistic but harmless and humorous buffoon to a menacing, murderous villain. Gaston was not a character in the original fairy tale. The 1946 French film did, however, feature the character of a handsome suitor, named Avenant, whom Belle rejected and who ultimately tried to kill the Beast. Disney claims to have added Gaston as a character to the film in order to create a heightened sense of danger as well as to showcase the theme of inner versus outer beauty.

Supervising animator Andreas Deja's initial drawings of Gaston were as an arrogant, burly, mustached man with a small brow and a large jaw. However, Jeffrey Katzenberg insisted that he be drawn more seriously to push the "don't judge a book by its cover" message. Deja revised his drawings with the idea of Gaston being more "soap opera handsome" than a typical casanova. The animator's interpretation would show that Gaston is superficially handsome, but ugly inside. Richard White, who finally won the role of voicing Gaston, believes many people were interested and auditioned for the role besides himself.

As Gaston believes he is the best man in town, he sets his sights on marrying the most beautiful woman in town, Belle. However, she refuses his proposal when he throws a wedding party without her prior knowledge. Thoroughly humiliated, he sulks, but when her father Maurice shows up claiming she has been captured by a hideous Beast, he comes up with the idea of having him thrown into an insane asylum, unless Belle agrees to marry him. His plan goes awry when Belle proves the Beast does exist, and she claims that he is her friend, and that he is a better person than Gaston. He becomes jealous and decides to gather a mob to kill the Beast, playing off the villagers' fears that the Beast might wreak havoc on their village. In the ensuing fight, he shoots the Beast with an arrow and beats him down, taunting him about his hideous appearance, and still refusing to believe that Belle will not marry him. The Beast has no heart to fight until he sees that Belle came back for him, when he easily overpowers Gaston and intends to kill him. However when Gaston begs for his life and claims that he will do anything, Beast is reminded of how Belle was willing to do anything, and chooses to spare his life, climbing back up to Belle. Gaston then stabs the Beast in the back, but loses his balance when the Beast swings his arm backwards at him; consequently, Gaston falls from the castle to his death. In an interview, White admitted that he did not even know whether or not Gaston died pointing out that Gaston was never seen to die, and so it was questionable if he actually survived the fall. However, a 2002 DVD commentary from the film's screenwriters confirmed his death.

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