Alagia or Alagía is a name. It can be both a given name and a surname, and can be found in both Italy and the United States.
Notable people with this name include:
Alagia Fieschi (fl. 1300s), an Italian noblewoman John Alagía, an American musician Tiziana Alagia (born 1973), a retired Italian runner
See also Alagiah, a similarly spelled Tamil name