A vampire was a creature from Earth mythology, a creature who had previously been a living Human, and had returned from death to feast on the blood of others. As with many legends, parts of this lore described real traits of actual creatures, and the term was often invoked whenever lifeforms who instinctively and necessarily feed on others are encountered.
In 2372, a Starfleet security chief on Earth likened a security officer to a vampire, as she was to perform a blood screening on him. She reminded him that vampires only come out at night. (DS9: "Paradise Lost")
In the script of the Star Trek: Deep Space Nine episode "Prophet Motive", Quark's reaction to Rom showing him Zek's revised version of the Rules of Acquisition was described in the stage directions as being "like waving garlic in front of a vampire".
A memo used as set dressing in "Far Beyond the Stars", and which he had apparently received from Douglas Pabst, suggested that "no one would believe that a cheerleader could kill vampires"; this was an in-joke referring to the fact Armin Shimerman appeared as a recurring character on the television series Buffy the Vampire Slayer. (Star Trek: Deep Space Nine Companion, p. 537)