Adriano Manuel Santos Niz (born 5 March 1986) is a Portuguese former swimmer, who specialized in freestyle events.
He is a single-time Olympian (2004), and currently holds a Portuguese record in the 4×100 m freestyle relay at the 2008 European Aquatics Championships in Eindhoven, Netherlands (3:23.06).
Niz also trains for Clube Fluvial Vilacondense, under head coach António Paulo Vasconcelos.Niz qualified for the men's 4×200 m freestyle relay, as a member of the Portuguese team, at the 2004 Summer Olympics in Athens.
Teaming with Luís Monteiro, João Araújo, and Miguel Pires in heat one, Niz swam a second leg in a split of 1:52.35, but the Portuguese team settled only for seventh place and fourteenth overall with a national record of 7:27.99.