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.

[2] After the 1916 Easter Rising, he joined Sinn Féin and campaigned at the 1918 general election for Roger Sweetman in Wexford North, even though his father was the sitting MP and Irish Parliamentary Party candidate.

[2] Thereafter Esmonde contributed to the Irish War of Independence by acting a diplomat for the new Sinn Féin shadow government.

After a period in London assisting Arthur O'Brien, Esmonde joined Eamonn de Valera in the United States where they sought recognition for the Irish Republic and resources to fund it.

Following a brief shore leave in Hawaii where Esmonde met the Irish-American governor of the islands Charles J. McCarthy in Honolulu, the Makura arrived in New Zealand in January of 1921.

Esmonde rejoined Cumann na nGaedhael in early 1927 but did not contest the June 1927 general election.

[2] By 1933 Esmonde had become part of the Army Comrades Association paramilitary organisation (better known as the Blueshirts), which had merged with Cumann na nGaedheal in September 1933 to become Fine Gael.

In November 1935, following the outbreak of the Second Italo-Ethiopian War, Esmonde proclaimed that he thought Benito Mussolini was the "Abraham Lincoln of Africa", whose mission was to "abolish the slave trade in spite of the sentimental sympathy of Great Britain".

[2] After his death aged 40 on 22 July 1936,[5] the consequent by-election for his seat in Dáil Éireann was held on 17 August, and won by the Fianna Fáil candidate Denis Allen.