Viscount Mount Cashell was a title that was created twice in the Peerage of Ireland.
He was made Baron Mount Cashell at the same time, also in the Peerage of Ireland.
For more information on this creation, see Earl Mount Cashell.
The title Viscount Mount Cashell was also created in the Jacobite peerage in 1689 in favour of Justin MacCarthy.
Paul Davys, who adopted the same title, had married Catherine MacCarthy, sister of the head of Justin's family, Donough MacCarthy, 4th Earl of Clancarty.