| Competition: | Alpha Ethniki |
| Season: | 1965–66 |
| Winners: | Olympiacos 16th Greek title |
| Relegated: | Panegialios Niki Volos |
| Continentalcup1: | European Cup |
| Continentalcup1 Qualifiers: | Olympiacos |
| Continentalcup2: | Cup Winners' Cup |
| Continentalcup2 Qualifiers: | AEK Athens |
| Continentalcup3: | Inter-Cities Fairs Cup |
| Continentalcup3 Qualifiers: | Aris |
| League Topscorer: | Mimis Papaioannou (23 goals) |
| Matches: | 240 |
| Total Goals: | 668 |
| Prevseason: | 1964–65 |
| Nextseason: | 1966–67 |
The 1965–66 Alpha Ethniki was the 30th season of the highest football league of Greece. The season began on 28 November 1965 and ended on 19 June 1966. Olympiacos won their 16th Greek title and their first in seven years.
The point system was: Win: 3 points - Draw: 2 points - Loss: 1 point.
| Rank | Player | Club | Goals |
|---|---|---|---|
| 1 | Mimis Papaioannou | AEK Athens | 23 |
| 2 | Giorgos Sideris | Olympiacos | 19 |
| Takis Loukanidis | Panathinaikos | ||
| 4 | Aris Papazoglou | Olympiacos | 18 |
| 5 | Stratos Sakellaridis | Panathinaikos | 15 |
| 6 | Alekos Alexiadis | Aris | 13 |
| Giorgos Koudas | PAOK | ||
| Vangelis Panakis | Panathinaikos | ||
| Kostas Papoutsakis | Panathinaikos | ||
| Apostolos Panopoulos | Egaleo | ||
| Onoufrios Charalampidis | PAOK |