August 20 is the feastday of a Saint Lassar associated with the area around Lough Lene in County Westmeath. She is alas, one of the many Irish saints about whom nothing much is known apart from the remembrance of her name and locality in the Irish Calendars. Canon O’ Hanlon has this to say:

St. Lasar, or Lassar, Virgin, of Cill Arcalgach, near Lough Lene, County of Westmeath.

…A festival in honour of Lasar, of Chill Arealgaich, is registered in the published Martyrology of Tallagh, at the 20th of August. Again, at the 13th of the September Kalends [i.e. August 20], that copy in the Book of Leinster spells the entry in a manner somewhat different [as Lassar o Cill Archalgach]. At this same date, the Martyrology of Donegal mentions Lassar, Virgin, of Cill Arcalgach,on the brink of Loch Lebenn, in Meath. Her place of residence must be sought for within or on the banks of the present Lough Leane—known in our ancient annals as Loch Lephinn or Loch Leibhinn. It is now called Lough Lene, about two miles and three quarters of a mile in length, by one mile in width and for its extent, it is one of the loveliest of the numerous lakes in Westmeath. It contains two wooded islets; and, on one of these, it is said a monastery formerly existed. Lough Leane lies about one mile south of Fore Village, in the barony of Demifore, and in the northern part of Westmeath County… The Irish Calendar now preserved in the Royal Irish Academy has a notice of this person as Lasar, Virgin of Cill Arcalgach, on the border of Locha Leibhean. We cannot attempt further to identify her, nor to know the period in which she lived.