Theobald mac Uilleag Bourke, 14th Mac William Íochtar (English: /bɜːrk/; BURK; died 1537) was an Irish chieftain and noble. Theobald was the son of Uilleag de Búrca and grandson of Edmund na Féasóige de Búrca, 4th Mac William Íochtar (d.1458). His brother, Edmond de Búrca, 12th Mac William Íochtar (d.1527), had been succeeded by a cousin, Seaán an Tearmainn Bourke, 13th Mac William Íochtar (the son of Ricard Bourke, 9th Mac William Íochtar), before Theobald became chieftain. Theobald was succeeded by his brother Edmond's son, David de Búrca, 15th Mac William Íochtar.