What's a dhampir? A vampir who can't afford a nice castle and lives in a damp basement apartment?
Have you heard about Blade?
Thats a Dhampir ...
Basicaly crossbreed between Vampire and Human (or mortal in this case probably, since they would be most likely be compatible with other humanoids aswell) ... there is many ways for them to be created, usualy ways differ across source material, aswell as their powers and weaknesses.