Hession (pronounced "hesh + in") is an old Connacht Irish surname.[1] It is an Anglicized form of Gaelic Ó'hOisin. In Gaelic, it is pronounced "O + hush + een".
It appears to originate in Co. Galway and in County Mayo. The Hession surname is predominantly found in these counties in the Census of Ireland, 1911. It means to descendant of Oisín a personal name meaning "little deer", and the name of the poet and warrior of the fianna in Irish mythology. Hugh Hession (Áed Ua hOissín) was the name of two Tuam clerics in the 11th and 12th Centuries - the coarb of St. Jarlath (1050) and first Archbishop of Tuam (1152) respectively. George Petrie who unearthed the High Cross at Tuam which bears an inscription Áed Ua hOissín wrote that he was assisted by a gentleman of the name O'Heshin who little realised he was digging up the relic of an ancestor. Darby O'Hession (spelt O'Hoysshynne) is the name of a Galway Cleric in the 16th, a vicar choral recorded in that churches first charter of St. Nicholas' Collegiate Church in Galway in 1551.
Hession has occasionally been spelt Hessian in Galway and is sometimes falsely assumed to be of German origin - See Hessian. The name may be related with similar names Hishon in County Limerick and Hassan in County Londonderry. Hishon is the anglicised from of Ó hOiseáin and finds an early reference amongst the Allies of the MacNamara family in Co Clare in the early 1300s. While Hassan may have an eastern look, it is the anglicized form of Ó hOsáin. Heshin, Hasson are also potential spellings. Lysaght suggests a connection with the surname Ussher - which is probably the name of a separate and distinct family of English Origin based in Dublin and later in Galway. This connection with Ussher is appaently the basis for claims the family is of Norman or English Origin, and the use of the Ussher Arms for the family on popular family history sites.
In the Monaghan Hearth Money Rolls of 1663 the name O'Hassan is recorded; two kings named Ua Oisin are recorded as kings of Mughdhorna in the region in the 8th century (see Airgíalla). There is also a Hasson of Wexford among the "principal gentlemen" of that county in 1598, but that family was no doubt of non-Gaelic stock and a John Hassan was an influential merchant in Wexford fifty years earlier.[2][3][4][5][6][7][8]