Invincible Incompetent: Sabrina went seven years without ever learning even one or two simple spells she could reliably not mess up. Notable in that there usually was no villain except for her mastery of this trope alternately causing and fixing problems.
Missing Mom: Sabrina's mother is mortal and is not allowed to have contact with her. She turns into a ball of wax if she sees Sabrina without approval from the Witches Council. In the series finale, the Witches Council does allow Sabrina's mom to attend her wedding, but demands that one of the aunts be temporarily turned into wax. Hilda volunteered Zelda and she is turned into a red candle.
Official Couple: With Harvey. A file from the X-Files Website later confirms that Aunt Irma - you know, the crazy lady with a temper that likes turning people into things - officiated the common-law wedding of Harvey and Sabrina and that they later lived in a house outside of Westbridge.
Flanderization: Hilda gets Flanderized from being the slightly more easy going of the two aunts to being a ditzy slacker. The best example is her music career: she goes from being a skilled orchestral violinist in the first season to having to be nagged into doing any practicing at all by her sister in the third.
Token Evil Teammate: He's still scheming and hoping to someday take over the world. Since he's a cat with no magic powers, however, his plans are usually limited to taking advantage of others in petty ways.
Troll: Has moments of this, particular on Sabrina, though she often retaliates. One time being a GIFT when playing online chess got him into trouble as one of the players he insulted came looking for him.
Verbal Tic: "Gyeeeh?" whenever he's surprised or shocked.
His characteristic sob when things don't go his way might also count.
Vitriolic Best Buds: With Hilda and (to a lesser extent) Zelda. They drive one another nuts on a regular basis, are always sniping at one another, and at times it seems like there's no love lost between them, but on a few rare occasions they do show that they care for one another.
The Bus Came Back: Left the show after Season Four, but made a handful of cameo appearances in Season Five, before he returned as a regular character in Season Six.
The Ditz: Occasionally he can be extremely clueless, but his heart is in the right place.
Give Geeks a Chance: A rare example of a female geek with a male hottie. Sabrina (Cool Loser though she may be) is the unpopular, science and math loving girl who ends up with popular jock Harvey. (Although most female geeks don't look like Melissa Joan Hart, Maxim covergirl.)
Romantic Runner-Up: In later seasons. That is, until the series finale, when he and Sabrina end up together. A file from the X-Files Website later confirms that Aunt Irma - you know, the crazy lady with a temper that likes turning people into things - officiated the common-law wedding of Harvey and Sabrina and that they later lived in a house outside of Westbridge.
Fate Worse than Death: In an episode where Sabrina began working as a temporary sandman and started invading people's dreams, she learned Libby actually enjoys going to high school because she can humiliate and belittle others. The next day Sabrina lied and told Libby she'd heard that she won a scholarship and would be studying abroad, out of a regular school. The mere thought of it completely horrified Libby.
Freudian Excuse: In "Five Easy Pieces of Libby", it's strongly implied that the reason Libby doesn't show compassion for other people is because it's never been shown to her.
Hidden Heart of Gold: It's been stated that Libby has yet to develop compassion or empathy for her fellow human beings, but it's been proven that she has a soft spot for and genuinely loves her grandmother, whom she goes to amusement parks with on her birthday to ride roller coasters.
Put on a Bus: He accepted a job in Prague as part of a spell to save Aunt Hilda, and he was never seen again.
Real Life Writes the Plot: The engagement and wedding storylines in Season 7 were written with him in mind. But, the actor wanted to move on to work in another series, so he was written out and the character of Aaron was created to fill that role.
Freudian Excuse: Roxie being the way she is gets explained in seasons 6 and 7 when we find out her mother was in prison for theft and her father and stepmother pay her no attention, resulting in her never even having a proper Christmas.
Calling the Old Man Out: During one of the Christmas episodes, Morgan calls her family out for being selfish and inconsiderate during the holidays even though she tries to make them happy, deciding she's had enough and refuses to take it anymore.