The Welsh surname Nanny or Nanney is locative in origin, that is to say derived from the name of a place or locality - in the present case the lands and house of Nannau, near Dolgelly in Merionethshire, which for many ages has been the home of the family. The Nanneys of Nannau are descended from Cadwgan Lord of Nannau, second son of Bleddyn ap Cynfyn, Prince of Powys, from whom the third royal tribe of Wales was descended. Howel Selyf or Sele, possessor of Nannau in the time of Owain Glyndwr, was ninth from Bleddyn ap Cynfyn; his grandfather, Ynyr Fychan (junior), son of Ynyr ap Meurig, presented a petition to the prince of Wales in the thirty-third year of Edward I's reign statng the King had made him Rhaglor of the comot of Talybont for his services in taking Madoc ap Llywelyn, who in the last war had made himself Prince of Wales. The petition was not granted as Ynyr could show no title or charter to the office. Hugh Nanney was head of the family during the first half of the seventeenth century and his name appears in the list of sheriffs of Merionethshire in 1627 and 1638. He died in 1647. The last of the line of Nanneys was his grandson, Colonel Hugh Nanney, Member of Parliament, Colonel of the Militia of his county and Vice-Admiral of North Wales in the last years of William III. He had no son and the Nanney estates were eventually inherited by Hugh Vaughan, eldest son of his third daughter, Catherine.
The Nanneys of Cefn Deuddwr were a branch of the great house but became extinct in the nineteenth century when the lineal representative, the Rev. Richard Nanney (died 1812) devised the estate to his sister's son, David Ellis, of Gwynfryn, Caernarvonshire. The latter died without issue and left the united estates of Geynfryn and Cefn Deuddwr to his sister's son, Owen jones, of Brynkir, who took after his own surname those of Ellis and Nanney.
The Nanneys of Maes-y-Neuadd, Merionethshire, were descended through the Wynns, of Glynn, from Osborne Fitzgerald, lord of Ynys-y-Maengwyn. Robert Wynn who was Sheriff of Merioneth in 1734 married the heiress of nanneys of Maes-y-Pandy in that country and his son and heir, William Wynn, assumed the name Nanney.
A Robert Nanney is said to have sailed from London for America in 1635 and he may well be the ancestor of the present day Nanneys of the United States. In the days when communities were small a person was identified by a single name only but with the increase in, and movement of, population, confusions arose and it became necessary to adopt a cognomen derived from one of four sources - the name of an ancestor, a place (of origin or residence), an occupation or some personal characteristic or nickname. Thus a man named John who was a member of the family resident of Nannau might be known as "John (of) Nannau or Nanney" in order to distinguish him from others of the same Christian name and in the course of time the cognomen became hereditary in what we now term surnames, ceasing to have any reference to the bearer's place of origin. The arms illustrated which may be described heraldically as Or, a lion rampant azure are ascribed to Cadwgan, Lord of Nannau, mentioned above, and used by the Nanney family by virtue of their descent from him. Writers in the past have attributed symbolism to the tinctures and charges of heraldry - thus or (gold) is said to denote generosity and azure (blue), loyalty and truth. The lion has always held a high place in heraldry as the emblem of deathless courage and therefore of the valiant warrior.