| Alan Diamonstein | |
| State Delegate: | Virginia |
| District: | 94th |
| Term Start: | January 12, 1983 |
| Term End: | January 9, 2002 |
| Preceded: | None (district created) |
| Succeeded: | Glenn Oder |
| Office1: | Chair of the Democratic Party of Virginia |
| Term Start1: | March 9, 1982 |
| Term End1: | June 14, 1985 |
| Predecessor1: | Owen B. Pickett |
| Successor1: | Richard J. Davis |
| State Delegate2: | Virginia |
| District2: | 48th |
| Term Start2: | January 13, 1982 |
| Term End2: | January 12, 1983 |
| Alongside2: | Ted Morrison & Bobby Scott |
| Preceded2: | Harvey Morgan |
| Succeeded2: | Mary A. R. Marshall |
| State Delegate3: | Virginia |
| District3: | 49th |
| Term Start3: | January 10, 1968 |
| Term End3: | January 13, 1982 |
| Preceded3: | Charles K. Hutchens |
| Succeeded3: | Robert Andrews |
| Birthname: | Alan Arnold Diamonstein |
| Birth Date: | 20 August 1931 |
| Birth Place: | Newport News, Virginia, U.S. |
| Death Place: | Newport News, Virginia, U.S. |
| Party: | Democratic |
| Spouse: | Beverly Hicks |
| Alma Mater: | University of Virginia |
| Allegiance: |  United States |
| Branch: | United States Air Force |
| Battles: | Korean War |
Alan Arnold Diamonstein (August 20, 1931 – October 17, 2019[1]) was an American attorney and Democratic Party politician.
Diamonstein served in the Virginia House of Delegates from 1968 to 2002, representing parts of Newport News. Diamonstein chose not to run for reelection in 2001, seeking instead the Democratic nomination for lieutenant governor. He came in second to Richmond mayor Tim Kaine, who would go on to win in the general election.[2] [3] Diamonstein was the chair of the Democratic Party of Virginia from 1982 to 1985.