Arguably one of the most iconic Disney witches of all time, The Little Mermaid's Ursula (Pat Carroll) was certainly one sassy and spooky witch. She only helps the "Poor Unfortunate Souls" when she's confident she can gain something in return. Case in point: Ursula temporarily granting Ariel's wish to be human. She literally steals Ariel's voice, and schemes to try and get the young girl to be her servant forever (thankfully she's ultimately unsuccessful). Not only is her attitude and bold personality on full display throughout the movie, but her evil laugh is truly the best.
10/10