Doeg the Edomite was Saul's chief shepherd or official who reported Ahimelech's aid to David and carried out Saul's massacre of the priests of Nob.
Biography
First Samuel 21 places Doeg at Nob when Ahimelech gave David consecrated bread and Goliath's sword. In chapter 22 Doeg reported the encounter to Saul. When Saul accused the priests of conspiracy and ordered his guards to kill them, the guards refused to strike the priests of the Lord. Doeg obeyed, killing the priests and devastating Nob. Abiathar alone escaped from Ahimelech's family and fled to David. Psalm 52's heading connects the psalm with Doeg's report to Saul.
Biblical Significance
Doeg is one of the starkest examples of ruthless loyalty to Saul's increasingly destructive rule. His actions contrast with the royal guards who refused an unlawful and sacrilegious command.