| Dag Usterud | |
| Nationality: | Norwegian |
| Birth Date: | 3 December 1961 |
| Birth Place: | Porsgrunn, Norway |
| Sport: | Sailing |
Dag Halfdan Usterud (born 3 December 1961) is a Norwegian sailor. He was born in Porsgrunn. He participated at the 1984 Summer Olympics in Los Angeles, where he placed fifth in the Soling class, together with Børre Skui and Stein Lund Halvorsen.[1]