Nir Welgreen (; born 17 December 1976) is a former professional tennis player from Israel.
His best performances on the ATP Tour were second round appearances at both Long Island in 1996 and Tashkent in 1997. At Tashkent he also made the semi-finals of the doubles in 1998, Vadim Kutsenko.
During his career he took part in several grand slam qualifying draws, including the 1999 Wimbledon Championships.
He won three ITF singles titles, two in Turkey and one in Ireland.
In doubles he had a top 200 ranking and claimed two Challenger titles.
| 1. | 1998 | Ahmedabad, India | Hard | Noam Okun | Noam Behr Eyal Ran | 3–6, 6–0, 6–4 |
| 2. | 1999 | Kolkata, India | Grass | Andy Ram | Grégory Carraz Guillaume Marx | 2–1 (RET) |
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