Thomas mac Edmond Albanach de Búrca, 2nd Mac William Íochtar (Lower Mac William or Mac William Bourke) (died 1402) was an Irish chieftain and noble who was lord of Lower (North) Connacht, Ireland.

A son of Sir Edmond Albanach de Burgh, 1st Mac William Íochtar (d.1375) and Sadhbh Ní Mháille (daughter of Diarmuid mac Owen Ó Máille), de Búrca succeeded his father as chieftain in 1375.

Thomas died in 1402, and was succeeded by his son Walter mac Thomas de Búrca, 3rd Mac William Íochtar (d.1440).

In total, Thomas had the following issue: From his son, Walter, descended almost all subsequent Mac William Iochtars and their successors.

[2] From the Annals of the Four Masters: