Vampire

A Vampire is a parasitic humanoid creature which feeds on the blood of living beings and causes their victims to turn into Vampires themselves. Traits typically associated with them include: sharp fangs, enhanced strength, aversion to sunlight and garlic, obsessive compulsive habits (such as an urge to count down small objects or to untie knots), a lack of reflection in mirrors and sometimes lack of shadows, and the ability to transform into animals or to become incorporeal. They are often described as "undead" creatures, inhabiting a deceased body.

Deriving from distinct folkloric legends of several cultures; the Vampire has become an increasingly popular phenomenon in the 20th century, influenced by works such as Sheridan Le Fanu's Carmilla and Bram Stoker's Dracula. Their aspect, nature, abilities and weaknesses have all varied immensely depending on the work they appear in. Vampires have been transposed to all sorts of media besides literature: in film too they have been popular since Count Orlok; in television it is hard to find a series dealing with the occult and the paranormal that doesn't feature them or at least touches on the subject. They have been present in comedy as well as horror; and every genre in between. As of science fiction, the vampire image has been used as inspiration for a myriad of extraterrestrial creatures, many of which are "vampires" in an analogous sense as they feed on something other than blood, as seen in the examples listed below. It is worth noting that the variety of vampires being so immense is also a result of simple linguistics as the word itself has become informally a near synonymous for parasites, real and fictional.

Aliens representing or inspired by vampires:
 * Extraterrestrial bloodsucking vampires are featured in the classic Doctor Who arc State of Decay; being the descendants of the massive Great Vampires of aeons past. They are distinct from the non-extraterrestrial Haemovores from The Curse of Fenric; and the Saturnynians who assumed an illusory humanoid appearance that resembled vampires in The Vampires of Venice.
 * Roger Corman's film Not of This Earth features the Davannans, a humanoid alien species which invades Earth and kills people for their blood as part of their attempts to cure themselves of a deadly epidemic. The victims are left bloodless and with distinct marks on their necks.
 * The Martian creature from It! The Terror from Beyond Space desiccates the bodies of its victims, leaving them completely dry of water and oxygen. This has been presented as a survival mechanism that helps it survive in the tough Martian ecology.
 * The Star Trek episode "The Man Trap" gave us the Salt Vampire, an entity which extracts salt from its victims' tissues.
 * The cartoon series Duck Dodgers features Count Muerte, a Fat Sucker, and a parody of the popular image of Dracula which seeks to drain his victims off their adipose tissue rather than blood.
 * The robotic "vampire" Nos-4-A2 from Buzz Lightyear of Star Command drains energy from electric machinery, including robots, which are placed under his control after being bitten.
 * Energy Vampires from the film Life Force are alien entities which feed on their victims' life essence.

Other blood-sucking aliens:
 * The Star Vampire, from Robert Bloch's The Shambler of the Stars is a blood sucker, but looks nothing remotely human. The Cthulhu Mythos provide a slightly more traditional take on the vampire myth in The Case of Charles Dexter Ward, but the vampiric entity there is not extraterrestrial.
 * H. G. Wells' Martians from The War of the Worlds might qualify as vampires, as they steal blood from Human victims to replace their own.
 * There have been UFOlogical reports concerning haematophagous creatures, including the particularly bizarre encounter Jennings Frederick had with a skeletal, blood-sucking plant-like entity in the woods of West Virginia, 1998. The mysterious Chupacabras is also a famous blood-sucker (although a rare example of one that doesn't seem interested in humans) believed to be of extraterrestrial origins by some.

Non-alien vampires:
 * Also worth mentioning are works which feature both aliens and vampires, but have little or no connection made between the two, including The X-Files, The Twilight Zone and Dark Shadows.