Some characters are unarguably on the side of Good and Right, wonderful to have around when needed. When not needed, you really do not to be around them. They're scary, disturbing, creepy, or just plain unpleasant. This trope rarely applies to anti-heroes, who tend to be only nominally or comparatively good.
Batman (except for the 50s/60s version). He's known as the Dark Knight, among other titles.
Granny Weatherwax. She's a good witch, no argument. But she's definitely not a *nice* witch.