Sir Osmond Thomas Grattan Esmonde, 12th Baronet (4 April 1896 – 22 July 1936) was an Irish diplomat and Cumann na nGaedheal (and later Fine Gael) politician.
Esmonde was first elected to the 4th Dáil at the 1923 general election as Cumann na nGaedheal Teachta Dála (TD) for the Wexford constituency. He did not contest the June 1927 general election, but was returned to the 6th Dáil in the September 1927 general election. He was re-elected at the 1932 general election, and again at the 1933 general election.
After his death aged 40 on 22 July 1936, the consequent by-election for his seat in Dáil Éireann was held on 17 August, and won by the Fianna Fáil candidate Denis Allen. He was succeeded in the baronetcy by his uncle Laurence Esmonde.