| Diarmuid Ó Gráinne | |
| Birth Date: | 10 May 1950 |
| Birth Place: | Aill an Phréacháin, Na Forbacha, County Galway, Ireland |
| Death Place: | Renmore, Galway, County Galway, Ireland |
| Occupation: | Writer, journalist, farmer, teacher |
| Nationality: | Irish |
| Genre: | Fiction, poetry, philosophy, criticism, translation |
| Subject: | modern Irish prose |
| Notableworks: | An Traimp, Muintir na Coille |
| Spouse: | Caitlín Ní Shíthigh |
Diarmuid Ó Gráinne (10 May 1950 – 28 August 2013) was an Irish-language writer and journalist from the County Galway Gaeltacht. He wrote for the newspaper, Lá and featured on Raidió na Gaeltachta. He released a number of books, perhaps best known works are his semi-autobiographical novel writings An Traimp and Muintir na Coille.
Ó Gráinne was strongly influenced by his fellow Connemara-man, Máirtín Ó Cadhain whose death he felt left a hole in the leadership of the Irish-language movement. Ó Gráinne also became interested in some Continental European authors, translating writings by or autobiographies about Karl Marx, Albert Camus and Friedrich Nietzsche into Irish.