If you were a werewolf or ate the meat of a sheep that was killed by a wolf, then you were definitely going to come back as a vampire after death. Obviously. Witches were also said to be close acquaintances of vampires, or at least those who practised dark magic were anyway, so their alliance meant that when the witch was burned at the stake, they would come back as a vampire. This one does seem a lot more problematic though as their bodies have turned to ash. But who cares about logistics? Mermaids were also considered to have vampiristic qualities and instead of preying on the blood of sailors, they would suck out their souls instead. Mermaids were apparently the original Dementors.
