Sicga (died 22 February 793) (also given as Siga and Sigha) was a nobleman in the Anglo-Saxon kingdom of Northumbria.
Sicga first appears in the historical record as senior lay witness to the proceedings of a council held by Papal Legate, George, Bishop of Ostia in 786, where he is called a patrician (), a term which may correspond with the Old English term ealdorman.
The Anglo-Saxon Chronicle records the murder of King ÃÂlfwald by Sigca at Scythlecester (which may be modern Chesters) on 23 September 788:<blockquote>This year Elwald, king of the Northumbrians, was slain by Siga, on the eleventh day before the calends of October; and a heavenly light was often seen on the spot where he was slain. He was buried in the church of Hexham.</blockquote>
Sicga's death, on 22 February 793, is recorded by the Anglo-Saxon Chronicle, and Symeon of Durham adds that he died by suicide. In spite of this, and the fact that he was a regicide, Sicga was buried at the monastery of Lindisfarne.