The Vampire Lord, also known as WzVAMP, is an enemy from the original Final Fantasy. They are found in the Flying Fortress and Temple of Chaos. They are of no real threat to the party (as none of the spells or abilities they have can threaten a party appropriate-leveled for the Fortress) and can be easily defeated.
There is a bug in the NES version that makes them even easier. Vampire Lords cast AFIR (NulBlaze). However, in the NES version, there is a bug that prevents elemental protection spells from working if the enemy that casts/gets affected by them is weak to the element it protects against. Vampires are weak against Fire, so AFIR will do absolutely nothing.
Vampires are mythological or folkloric beings who subsist by feeding on the life essence, generally in the form of blood, of living creatures. Although vampiric entities have been recorded in many cultures, and may go back to "prehistoric times", the term vampire was not popularized until the early 18th century.