Passive euthanasia is something I deem fair. I mean, more often than not, it's presumed that there's no hope and death is better than suffering for a few more days. As for active euthanasia, that's a harder spot. I'm not sure where I stand on the death penalty, but I feel like it's not right. Not sure if that counts as euthanasia, though.
Odd, though, cause this reminds be of the episode of Walking Dead where Dale got euthanized. In a situation like that, I'd totally be for it. The alternative is just too cruel, in my opinion. That's fiction, though.