Stephen Antunes Eustáquio (born 21 December 1996) is a Portuguese footballer who plays for G.D. Chaves as a midfielder.
Born in Leamington, Ontario to Portuguese parents, Eustáquio returned to Portugal at a young age to finish his development. To start his senior career, he spent two full seasons in the third division with S.C.U. Torreense after beginning in amateur football with Grupo Desportivo Os Nazarenos.
On 7 June 2017, Eustáquio signed with Leixões S.C. for an undisclosed fee. His first game as a professional occurred on 23 July in a 2–0 home win against Académico de Viseu FC for the season's Taça da Liga where he played the full 90 minutes, and his debut in the Segunda Liga was on 6 August in a 1–4 away loss to Real SC.
On 31 January 2018, Eustáquio joined G.D. Chaves on a five-and-a-half-year deal after his buyout clause of €500,000 was paid. He made his Primeira Liga debut four days later, playing the entire 2–1 away success over C.D. Feirense.
In November 2017, Portugal under-21 manager Rui Jorge called Eustáquio for 2019 UEFA European Championship qualifiers against Romania and Switzerland to be held early in that month. He won his first cap on the 10th against the former, playing the full 90 minutes and being booked in the 1–1 draw in Constanța.
Eustáquio's older brother, Mauro, is also a footballer. A midfielder as well, he represented Canada at under-20 and under-23 levels.