A wizarding family. A Notable member of the family is:
Levski means "like a lion" in archaic Bulgarian (modern Bulgarian lăv) and the name Lev means "like a lion" in Russian and several other Eastern European languages (Baby Namespedia: Lev).
The currency of Bulgaria is a "lev" and there are lions featured on the notes and coins (Wikipedia: Bulgarian lev).
The name could also have been inspired by the Bulgarian hero Vasil Levski (Vasil Ivanov Kunchev, 1837-1873) (Wikipedia: Vasil Levski).