Aleksandr Grebenyuk (Russian: Александр Гребенюк; born 22 May 1951 in Zelenokumsk, Stavropol Kray) is a retired decathlete from the Soviet Union. He set the best world's year performance in 1977, collecting 8400 points at a meet in Riga on 3 July 1977. He won the European title in 1978, and collected three Soviet titles (1977, 1978 and 1979). His cousin is Ekaterina Grebenyuk, future physician.