- A family originally from Munster who purchased land in the barony of Erris, county Mayo, in the early 17th century. One of their main strongholds was the castle at Inver. Some deeds in the Westport Papers document their activities in 17th century county Mayo, including their purchase of a large estate in the barony of Erris, from the Brownes in 1700. The Cormacks were also the head tenant of more than 30,000 acres in the barony of Tirawley which was mortgaged by the Brownes to Richard Thompson and included more than 28,000 acres known as the Commons of Crossmolina. By the 18th century the Cormacks were residing at Castlehill and Mullinmore in the parish of Crossmolina, barony of Tirawley. Captain Michael Cormick is listed as an absentee proprietor for the barony of Burrishoole in the Statistical Survey of 1802. Major Michael Cormack of Castlehill died in 1835 and his property passed to his two sisters, who were married to Edmond Coyne of Farmhill, county Roscommon, and John Walsh of Hume St, Dublin. Walsh had Castlehill and added the name Cormack to his surname.
- The Coynes inherited lands in the parishes of Kilcommon and Kilmore, barony of Erris and in the parishes of Addergoole and Crossmolina, barony of Tirawley, county Mayo, from the Cormack family. They leased the lands of Massbrook to the Jones family of Ardnaree. In 1876 Charles M.Coyne owned over 8000 acres in county Mayo and Bernard Coyne had another 1816 acres.
- In the late 1830s the Walshes inherited part of the Cormack estate in the parish of Crossmolina, barony of Tirawley, and in the parishes of Kilcommon and Kilmore, barony of Erris, county Mayo. In 1876 John Cormack Walsh owned 6472 acres in the county. The Congested Districts' Board purchased over 1000 acres of the Walshes property in November 1906 and part of the Iniskea Islands in 1907.