As I asked the question about whether or not modern day vampires were merely super heroes, it got me wondering:
Where is the first depiction of a vampire who does not kill humans? In other words, a vampire who must drink blood to survive, but has enough of a conscience that he or she takes steps to avoid killing anyone.
There are three possibilities for this, one is that they drink blood without killing the person (drinking human blood from blood bags would fall into this category). Another is drinking from animals. The last is a technological solution, such as having synthetic blood as a replacement for human blood, or any other workaround that is built out of engineering.
The main issue is who is the first vampire to not want to kill humans to survive, so any of the three methods would count. However, as a bonus, it would be interesting to know the first occurrence of each.
Also, it has to be a vampire who not merely regrets killing humans, but actually survives somehow without killing humans.
Any media counts - books, movies, TV, short stories, comics...
Traditional folklore, if it applies, would be interesting to note, but the focus of this question is on specific nameable works of fiction, since folklore is so malleable.
Also, we're looking for a character that is undeniably a vampire. Damphirs (half human, half vampire), humans infected with vampire blood but not fully realized vampires (perhaps not undead yet), or other variants don't count. Yes, I realize there could probably be a lot of debate on what counts as a "true" vampire, but let's try our best to come to a consensus on it.