Betty Quinlan is Jimmy's first love interest before having Cindy as his. Betty is implied to be slightly older than Jimmy and his friends, who first appeared in the episode Party at Neutron's.
Jimmy almost openly displays his attraction for Betty.
Betty seems to return to Jimmy's flirting throughout the series, as if she is (or was) slightly attracted to him, much to Cindy's jealously and irritation.
Betty is known to enjoy magic, acting, singing (as she is in the choir in "Attack of the Twonkies" not seen talking), and dancing.g
Betty's second appearance was in "Out Darn Spotlight," in which she proved herself to be a talented actress, as she was given the role of Lady Macbeth in "Macbeth in Space."
Nick originally starred-opposite Betty, playing Macbeth, but Jimmy was forced to take over the role after Nick was injured. In this episode, Betty is Jimmy's motive for wanting to be in the play so badly, and she seems to know this, and offers him kind encouragement. However, Cindy doesn't seem irritated in this episode about the nature of Jimmy and Betty's interactions. Towards the end of the episode, Betty gives Jimmy a kiss, as they had not gotten to do on stage, making Jimmy's infatuation with her grow larger and stronger. She was also in an episode featuring an old grandma who was actually an alien called "One of us".
Betty's third appearance was in "Vanishing Act," in which Jimmy attempts to perform a magic show in order to impress her. However, the magic show goes awry, and they end up stuck in another dimension. Jimmy and Betty continue to flirt, as they did in previous episodes. This is the episode, in which Cindy's noticable jealously peaks, and she furiously attacks Betty over it. Betty calmly pulls her aside and explains that she is not interested in Jimmy, telling her to stay "out of her face", and that Jimmy is "all (Cindy's)." This ends with the large-scale conflict between Cindy and Betty, as well as all of the flirting between Jimmy and Betty. It also implies that while Betty might be touched with Jimmy's affections, she just sees him as a friend. Though the way she said it sounds as if she might have a slight antagonistic side of taking advantage of Jimmy's affections. Because of this, Cindy possibly dosen't want Jimmy to have his feelings hurt and she actually cares about him, Which made herself get devoured by a Giant Eel.
In addition to the appearances mentioned above, Betty often makes cameo appearences in the background with other kids from Retroville, and she was included in "Operation: Rescue Jet Fusion" as Jimmy's object of affection, though only in his daydreams, and she never appeared in person. In "Jimmy Timmy Power Hour 2: When Nerds Collide!" she made a brief cameo at the beginning. However throughout most of the episodes Neutron has pictures of her stashed throughout his lab, which later Cindy made him get rid of all of them. She is voiced by Kath Soucie.
