The Sheild is: Gules, three lions passant in pale or and argent.
The Crest is: None
The Motto is: "The Strong Hand Uppermost"
Variant spellings for Downey: Downy, Dawney, Doheny, Dowling, Mac Downey, MacEldowney, Maloney, Moloney, Mullowney, Muldowney, Gildowney, O'Downey, O'Muldowney, and O'Moloney.

The O'Downeys were of some importance in early mediaeval times, when there were two distinct septs of O'Dunadhaigh. That of Sil Anmchadha, of the same stock as the O'Maddens, several of whom are described in the "Annals of Innisfallen", "Four Masters" etc., as lords of Sil anmchadha, became submerged as early as the twelfth century.

The most numerous of the Downey name today are of the Luachair sept, springing from the contiguous areas of Cork, Kerry, and Limerick. Luachair was the name of an old geographical division comprising that modern day area. Here the O'Downeys ruled as chiefs. Some have changed the name to Dowling in this area, which is a popular name in Co. Kerry.

A separate family of O'Downey hails from Co. Galway, and they were known in ancient times as 'Lords of Sil Anmchadha'. They are of the same descent as the O'Maddens.

'Mac Downey' or more precisely MacEldowney, a name of Co. Derry, is an Ulster name of separate origins. It is sometimes found simply as 'Downey', stemming from Mac Giolla Domhnaigh.

Muldowney is also found in Co. Down. Of other related names, Gildowney and Downey were synonyms in Newry Union, County Down at the close of the last century.

O'Molony and O'Muldowney have also been used interchangeably on occasion and of course those who were originally Muldowney, Gildowney etc,...have at times shortened the name to Downey. Muldowney has been found often in Co. Kilkenny.

In Co. Cork Downey and Dawney are sometimes used for the popular name of Doheny.

In the 1890 birth index Downey was found most often in Cork, Kerry, Antrim, Galway, and Limerick. The distribution is shown below.
Births of the surname in 1890 (by province): Leinster 16, Munster 42, Connacht 11, Ulster 22.

In modern times few Downeys have been noteworthy. The best known was Most Rev. Richard Downey (1881-1953), Archbishop of Liverpool.

Sources: The Book of Irish Families Great & SmallIrish Families: Their Names, Arms, and Origins
Michael C. O'LaughinEdward MacLysaght
1997 Irish Genealogical FoundationIrish Academic Press Limited 1991