| Gregory Deighan | |
| Birth Date: | 15 October 1939 |
| Office: | 28th Speaker of the Legislative Assembly of Prince Edward Island |
| Premier: | Pat Binns |
| Lieutenant Governor: | Léonce Bernard Barbara Hagerman |
| Term Start: | November 12, 2003 |
| Term End: | July 5, 2007 |
| Predecessor: | Mildred Dover |
| Successor: | Kathleen Casey |
| Office1: | Member of the Legislative Assembly of Prince Edward Island for Wilmot-Summerside |
| Term Start1: | November 18, 1996 |
| Term End1: | May 28, 2007 |
| Predecessor1: | Riding Established |
| Successor1: | Janice Sherry |
| Party: | Progressive Conservative |
| Residence: | Summerside, Prince Edward Island |
Gregory "Greg" J. Deighan (born 15 October 1939)[1] was the Speaker of the Legislative Assembly of Prince Edward Island, Canada. He was a member of the Progressive Conservative Party, representing the Wilmot-Summerside electoral district.
In May 2000, Deighan was appointed to the Executive Council of Prince Edward Island as Minister of Tourism.[2] In August 2002, Deighan was moved to Minister of Fisheries and Aquaculture.[3] He served as Speaker of the Legislative Assembly from 2003 to 2007.[4]
He did not stand for re-election in the 2007 general election.[5]