Vlad the Impaler
Vlad the Impaler, V, is a unique vampire notable in that he holds the Candelabrum of Invocation. He resides at the top of his tower in Gehennom. Like his weaker brethren he possesses the abilities of flight and magical breathing. He is also covetous, which means he will warp to the ladder down to heal. He is always generated with a two-handed sword, a battle-axe, a bow and 3-14 arrows, or, with a 21% chance, nothing.
Vlad is the second fastest monster in the game, faster than a player with speed boots. His speed allows him to warp to you, hit you, bite you, and sometimes warp away again in a single turn before you get a chance to retaliate. And contrary to other covetous monsters, if you are standing on the ladder yourself, he will warp away a few steps when hurt instead of staying next to the ladder. If you take the bait and follow he may then escape down. This, combined with around 130 HP, makes it quite frustrating to fight him.
He hits hard, and often gets multiple hits for each of yours. Above all he deals double damage during the midnight hour (0:00-0:59 server time) due to being undead. The quickest way to deal with him is to stone or paralyze him. If neither of the two is available, you need decent AC and a well enchanted silver weapon to take him down quickly. Unfortunately he is immune to sleep.
Be careful not to confuse Vlad: if he levelports by a confused scroll of teleportation, you get to look for him in his Tower, all of Gehennom above it, and the entire Dungeons of Doom, which is very annoying. You better not use Magicbane on him.
Prior to 3.6.1, Vlad used to be significantly slower, weaker and wouldn't teleport away. He was widely regarded as being quite a feeble enemy to be a mandatory fight at the stage of the game when he is faced; he was not significantly stronger than the vampire lords which appear as normal enemies.
Jokes abounded of fighting him with food rations, thoroughly rusty thoroughly corroded tin openers (which could still rust back then), or not moving every second turn while fighting him, or a variety of other absurd scenarios which would normally result in YASDs, and still easily defeating Vlad. The items used for such exploits had become known as Vladsbanes (or Vladbanes or Vladsmashers, in a mockery of the Banes) and on the occasions when such an item is used it is often so #named in tribute (see link below). The danger of confused levelport by Vlad even gave you a legitimate reason to use a Vladbane-type weapon instead of Magicbane.
A variety of patches had been written to address this issue by altering Vlad in some way. One of the better known ones was the aptly-named Vlad Balance patch. The Dudley's dungeon strip for 30 November 2006 (via Wayback Machine) featured several humorous attempts to remake Vlad; see also the comments for the 30 November and 1 December strips.