Donato Bago Guimbaolibot (December 5, 1866 – September 9, 1949), also known as Padre Atoy, was a Filipino Catholic priest known for his efforts in developing the town of Guiuan in present-day Eastern Samar and for his involvement with the Balangiga Massacre controversies.

[1] He completed his primary education in Guiuan and, with the support of his parents, he later studied for the priesthood at the San Carlos Seminary in Cebu.

[1] He was elevated to monsignor where he was first-ever priest in the Diocese of Calbayog and was conferred the honorary title of Supernumerary Privy Chamberlain (Domestic Prelate) on January 24, 1930.

[1][7] Up to date, the Roman Catholic Dioceses of Borongan and Calbayog has not released any official statement regarding the possibility of formally opening his cause.

Guimbaolibot is mentioned in Gina Apostol's 2018 novel, Insurrecto, a narrative retelling of the Balangiga massacre by a Filipino translator and an American filmmaker.