* EnsembleDarkhorse:
** Miss Bat is the most popular of the teachers with fans. It's quite surprising given that she made one appearance in the books. Likewise Drucilla was well received - enough for Jill Murphy to feature her more in books that were written after the TV series.
** For non-book characters, Charlie Blossom as well - presumably for the {{Shipping}} potential. One episode character Deirdre Swoop also got upgraded to regular in both spin-offs.
* FridgeBrilliance: Ethel gives herself a "witch-over" in season 2 because she's embarrassed by her sister (explaining why she is played by Katy Allen). However in ''Weirdsister College'' she is played by Felicity Jones again. Now she's at college where her sister isn't there, she doesn't have to worry about being embarrassed by her so she removed the "witch-over".
** Likewise Deirdre Swoop doesn't recognise Ethel in the first episode because she had only seen her witch-over self.
** It's stated in the first episode that the right words in spells aren't as important as the right feelings. Episode three deals with Ethel being turned from a pig into a duck by Charlie getting the spell words wrong. The brilliance is that Charlie has not been educated in magic at all so he can't rely on "the right feeling" - so all he can go on are the words to the spell. Alternately he might have been concentrating on "turn Ethel back from a pig" but not concentrating enough on what to turn her ''into''.
*** Closely related is Enid's spell for food in "Let Them Eat Cake". Like Charlie, the spell fails because of the last word. Both she and Charlie put emphasis on the last word in the incantation - resulting in the wrong effects. Charlie says Reduccio as "re-DUCK-io" so Ethel is turned into a duck. And Enid says "make it hasty" and gets them showered with hay.
**** Also for Enid's spell - hay can be a snack for animals. Enid just wasn't being specific enough that she wanted food for herself.
** Why are spells in Latin when any incantation will do (coupled with the right feeling)? Because Cackles prides itself on tradition and Latin was what the upper classes wrote books in back in the days the spells were invented.
* LesYay: In ''The New Worst Witch'', Dyllis Mustardseed seems to be crushing pretty hard on Belladonna Bindweed. Too bad Belladonna hates her.
* {{Narm}}:
** Merlin trying to reseal the Dragon Lord back into the cave. He says "Back from whence you came" as if he couldn't care less.
** Miss Drill's evil persona as Hilary Hemlock. EvilIsHammy to the last degree.
** While Sybil is an effective Woobie, any time she actually has to cry on screen, it's painfully forced.
* OlderThanTheyThink: An isolated medieval castle containing a magic school, with a forest nearby? A protagonist who has no prior knowledge of the magical world? A rival who comes from a leading magical family? A hook-nosed Potions teacher who favours the rival and despises the protagonist? A kindly, grey-haired Head who befriends and helps the protagonist? Classes in Charms and broomstick riding? While both ''The Worst Witch'' and ''Harry Potter'' clearly have very similar elements, Jill Murphy's series predates the latter by 23 years, with the first book being published in 1974.
* PainfulRhyme: Tim Curry's big song features every conceivable word that rhymes with "Halloween," and many that aren't.
* ReplacementScrappy:
** Katy Allen for Felicity Jones as Ethel. Likewise Ted Blossom being an {{Expy}} of his brother Frank. Averted with Miss Crotchet, despite replacing the fan favourite Miss Bat.
** In ''Weirdsister College'' Cas Crowfeather gets a bit of hate for replacing Maud as Mildred's best friend.
** Caroline O'Neill replacing Kate Duchene as Miss Hardbroom in ''The New Worst Witch''.
* SoBadItsGood[=/=]SpecialEffectsFailure: The music video made by Tim Curry aka the Grand Wizard. [[http://www.youtube.com/watch?v=PUhuPn8_d0Q Really, see for yourself.]]
* TearJerker:
** The episode "Good Friends" of ''Weirdsister College''. Enid shows up at Weirdsister and, while she and Milly have fun at first, it's soon apparent that they've gone in different directions. And in the end the girls both realise that they can never be friends in the way they were back at Cackle's. TruthInTelevision sadly, as many people outgrow the friends they had in school and lives head in different directions.
** 'Miss Cackle' going ballistic and locking Mildred in her room in the season 1 finale. Mildred gets dragged from the classroom by her ear, abuse yelled at her in the office and is confined to her room just after she's told she's expelled. Even Miss Hardbroom is shocked by this behaviour. The kicker is that this is triggered by Ethel pranking Mildred in class. It's made a little better since [[spoiler: it's only Agatha Cackle impersonating her sister]].
** The end of the first Halloween episode - as Ethel casts a spell on her broomstick to humiliate Mildred. It's slightly worse than in the book - where Mildred is bucked off and causes the other girls to fall off as well. Here it's ''only'' Mildred that gets humiliated and she crashes into the Grand Wizard. The book also only says that "even Maud was being very cool towards her friend" - but the TV series has Maud outright ignore Mildred after it happens.
* TheyWastedAPerfectlyGoodCharacter: Ruby zigzags through this. While she does get a couple of more focus episodes as the series goes, she's still very much an obvious TokenMinority. Jadu meanwhile gets only one day in the limelight - which is the second last episode. In this case it's slightly justified by her actress just not being very good.
* TheWoobie:
** Sybill Hallow. Mildred herself also has some aspects of this.
** Dyllis Mustardseed in ''The New Worst Witch.''