Eusebiu Iancu Diaconu (born March 16, 1981, in Bacău) is an amateur Romanian Greco-Roman wrestler, who played for the men's lightweight category.

Diaconu made his official debut for the 2004 Summer Olympics in Athens, where he reached the knock-out stage of the men's 60 kg, by winning the preliminary pool round against U.S. wrestler Jim Gruenwald and Portugal's Hugo Passos.

He lost the quarterfinal match to South Korea's Jung Ji-Hyun, with a final score of 0–6.

[5] Because his opponent advanced further into the final match, Diaconu offered another shot for the bronze medal by entering the repechage bouts.

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