Bermingham, Peter (Piers) of Athenry (d. 1309?), Anglo-Irish baron, was the son of Meiler de Bermingham and a member of the important Bermingham family originally settled at Tethmoy, Offaly; he has often been confused with Peter Bermingham (qv) of Tethmoy (d. 1308). In the late 1230s Meiler de Bermingham obtained from Richard de Burgh (qv) (d. 1243) a direct grant of lands around Athenry, Co. Galway, where he apparently built a walled town, settling his followers there and in the adjacent area. Peter had at least one brother, William de Bermingham (qv) (d. 1312), later archbishop of Tuam, and one sister, Basilia, who married Stephen fitz Jordan de Exeter, lord of Athlethan, Co. Mayo.
The first reference to Peter in the annals may be that to an unnamed Bermingham lord, who in 1261 insulted the O'Haras (Uí Edra) by violating the church of St Feichin at Ballysadare. Domnall O'Hara swiftly revenged this raid by ravaging the Bermingham lands, killing one Sefín (little Geoffrey) de Bermingham. In 1285 Peter attacked and killed Ruaidrí O'Gara, king of Sliab Luga (Mayo and Roscommon), on his own island, and in 1289 he and the de Burghs murdered Fiachra O'Flynn of Síl Mailruain. The stock of the Berminghams continued to rise, as the election in 1288 of Peter's brother, William Bermingham, to the archbishopric of Tuam suggests. It seems that Peter sided with Richard de Burgh (qv) (d. 1326), the Red Earl of Ulster and lord of Connacht, in his struggle during the 1290s against John fitz Thomas FitzGerald (qv) (d. 1316), later earl of Kildare. That Peter of Tethmoy remained closely associated with fitzThomas does not appear to have affected his relationship with Peter of Athenry: between 1299 and 1305 the two were repeatedly called to serve in the campaigns of Edward I against the Scots, and served in Scotland during 1301.
The identity of Peter of Athenry's first wife has not been established; his second wife may have been Maud, daughter of Richard of Rokeby. He had at least two sons: Meiler (d. c.1302) and Richard (d. 1322). According to Orpen, he ‘seems to have died soon after his cousin of Tethmoy’, who died in 1308; it appears that he was the Bermingham said by the Gaelic annalists to have been killed in 1309 in Connacht by Ruaidrí O’Connor and O'Flynn.