- The Dillon family held a large estate on the border of counties Mayo and Roscommon. They were descended from the Norman family who had first become established in county Westmeath. Theobald Dillon of Loughglynn was granted over 4,700 acres by patent in December 1680. The main part of their estate was in county Mayo where they owned extensive lands in the parishes of Aghamore, Annagh, Bekan, Castlemore, Knock, Kilbeagh, Kilcolman and Kilmovee in the barony of Costello. At the time of Griffith's Valuation, Anne McDonnell was leasing over 130 acres from the Dillon estate at Calveagh, barony of Costello. In 1876 Viscount Dillon owned 83,749 acres in county Mayo, 5435 in county Roscommon and 136 in county Westmeath. He sold his estate in counties Mayo and Roscommon, amounting to 93,652 acres, to the Congested Districts' Board on 11 May 1899.
The Stricklands were agents for the Dillon estate. In 1828 Jerrard Strickland of Loughglynn was a member of the Grand Panel of county Roscommon.
- At the time of Griffith's Valuation William Calvert held lands in the parish of Clooncraff, barony and county of Roscommon, parts of the estates of Gilbert Conry and James Dillon. Lands amounting to 172 acres in the parish of Kilgefin, barony of Ballintober South, county Roscommon, the estate of William Calvert, were advertised for sale in June 1866 on his own behalf and as trustee for sale for George and Joseph Walpole. The sale included larger acreages in county Tipperary and King's County (county Offaly). In the 1870s William Calvert of Monkstown, county Dublin, owned 1,180 acres in county Roscommon.
- A family of Taaffe were established as landowners in the Strokestown area from the 18th century. Gerald Dillon writes that they were apparently a junior branch of the Taaffes of Smarmore Castle, county Louth. In the mid 19th century Patrick Taaffe held lands in the parishes of Elphin, Killukin and Kiltrustan, barony of Roscommon, from a number of land owners but mainly from Christopher French of Cloonyquin and James Dillon. Joanna and Julia Taaffe offered over 600 acres in county Mayo and over 1000 acres in county Roscommon for sale in the Encumbered Estates' Court in June 1856. The Mayo estates were in the barony of Costello while the Roscommon lands were in the barony of Frenchpark and were formerly the estate of Christopher Taaffe, deceased. The Mayo lands were purchased by Mr.O'Hagan in trust while the Roscommon lands were purchased by Mr. O'Grady. In the 1870s Patrick Taaffe of Foxboro, Tulsk, owned 171 acres in county Roscommon. The estate of Joseph Plunkett Taaffe in the parishes of Killukin and Kiltrustan was advertised for sale in June 1883. The Irish Times reported that this property had been purchased in trust on behalf of Dr. Scallan for £2000. Gormley states that the Taaffes had formerly been an influential family in the area but had lost their inheritence thorough maintaining a lavish lifestyle. Members of this family are buried in the graveyard of Tulsk Abbey.
- In the late 18th century Patrick Dillon owned land in the parishes of Clooncraff, Killukin and Kiltrustan, barony and county of Roscommon, some of which he leased to George Taaffe and James Begg. These lands amounting to over 1,000 acres, the estate of James Dillon, were advertised for sale in June 1853 and February 1854. In June 1855 a further 500 acres of James Dillon's estate, at Brackloon, parish of Kilcorkey, barony of Castlereagh, was advertised for sale in the Encumbered Estates court. It was the subject of chancery proceedings at the time.