Arguably walpurgisnacht might be Houmura witch (gears, appears suddenly as warped from the future, is the other half of kriemhild gretchen, is always stronger than puella mage Houmura...) In that case the end might be strangely happy... for them at least.
The record probably ought to be set straight on this for future commenters; Walpurgisnacht is, officially and explicitly, not the Witch form of Homura. It's a conglomeration-type Witch that arose from a number of other Witches melding together, and has existed for a very long time as a sort of roving disaster.