Efstathios Papadionysiou, commonly known as Stathis Papadionysiou (Greek: Ευστάθιος "Στάθης" Παπαδιονυσίου; born September 15, 1992) is a Greek professional basketball player.
At a height of 1.97 m (6'5 3⁄4") tall, he plays at the shooting guard and small forward positions.
Papadionysiou began his pro career in the 2013–14 season, with AEK Athens of the Greek 2nd Division.
After that, Papadionysiou played with the Greek clubs Pagrati Athens (2015–16), Aiolos Astakou (2016–17), Iraklis Thessaloniki (2017–18), and Charilaos Trikoupis (2018–2020).
While he was a member of Charilaos Trikoupis, he won the Greek 2nd Division championship, in the 2019–20 season.