Knockvicar (Irish: Cnoc an Bhiocáire) is a village in County Roscommon, Ireland. It is located on the R285 regional road, between Boyle and Carrick-on-Shannon near Lough Key Forest Park in the north of the county. Knockvicar lies on the Arigna Scenic Drive off the N4 road from Dublin to Sligo It is where the actress Maureen O'Sullivan spent part of her youth. In the late Middle Ages Knockvicar was the location of a Franciscan Priory.