Maolmhuaidh is an Irish surname, generally anglicised as Molloy or Mulloy.
The male version is Ó Maolmhuaidh with the name in the genitive or possessive case preceded by ("ó" or “ua” meaning "grandson or descendant"); the female versions is Ní Mhaolmhuaidh ("ní" a contaction of “iníon” meaning "daughter”, there is no equivalent of Mrs as women in gaelic society retained their maiden names after marriage); the family or house name is Uí Mhaolmhuaidh “uí” being the plural of “ua” or “ó”.
The Uí Maoil Aodha ("descendant of the devotee of (St.) Aodh") family lived in east Connacht and is now found as both Mullee and Molloy.
The Uí Maolmhaodhóg ("descendant of the devotee of (St.) Maodhóg") surname is now usually rendered as Mulvogue or Logue, but sometimes Molloy, particularly around the Glenties area of County Donegal.
The 1890 registration of births found bearers of the surname concentrated in counties Donegal, Dublin, Galway, and Mayo.