well, it depends what you mean, you talking Harry Potter witch who is fighting an all powerful dark witch? no.
we all have the ability to become powerful spell casters for 'good' or 'evil'. once you're able to cast, you can defeat/dispel/protect against 'evil', cure people depending on the illness, and solve most problems. but a witch who appears in a bubble, taps someone with a wand and magically cures them of cancer, no.
you need to know the difference between real magic and faerie tale magic. real magic is energy, you cannot see it working, but it works to help us with life. faerie tale magic can turn people into newts. [which would be fun sometimes but can't happen lol] why do you ask?
no, there's usually no witches that can do this, there are some extremist witches that do attack and try to steal powers from everybody but this is both wrong to do and dangerous, also lots of karma falls upon them, most witches just want to improve their lives, solves their problems, control their lives, or defend themselves against dark and negative spirits or people, witches usually fight only in self defense, they believe do no harm and the 3 fold law, if their was such a witch I would imagine they would be a spiritual and perhaps a physical vigilante which no offense to them but they probably get their butts beat up a lot either spiritually or physically, witches are meant to make a world a better place for the greater good, not for destruction, even if they mean good, it's destroys people or peoples lives when you go around curing, cursing, and stealing peoples stuff or to people or it's harmful to protect everyone because you only need to protect yourself, not only does it protect yourself, but it also stops violence, wars and hate, It's like a law to do no harm, also if someone was doing that they would have to bare all the evil of a person upon their shoulders which I would think it would feel like hell, literally, also not to mention even though it's not like the middle ages and the salem witch trials I have heard that people do still become witch hunters, at least that's what I've heard, kind of like how crazy people believe their are vampyrs and they try to kill and slay them and how werewolf hunters try to kill werewolves, of course even though there are witch hunters no matter how hard they try to cover evidence a murderer always gets caught and they know that and they always are brought to justice and often have a miserable life in prison waiting for death to come, so I do believe there are some witches that try to hurt people with curing spells, but it's not often or less likely to happen.