Óengus mac Óengobann, better known as Saint Óengus of Tallaght or Óengus the Culdee, was an Irish bishop, reformer and writer, who flourished in the first quarter of the 9th century and is held to be the author of the Félire Óengusso and possibly the Martyrology of Tallaght.

The Martyrology of Tallaght, which is closely related to the Félire Óengusso or Martyrology of Óengus the Culdee, is an eighth- or ninth-century Irish-language martyrology, a list of saints and their feast days assembled by Máel Ruain and/or Óengus the Culdee at Tallaght Monastery, near Dublin. The Martyrology of Tallaght is in prose and contains two sections for each day of the year, one general and one for Irish saints. It also has a prologue and an epilogue.