Who did King Saul offer as a wife
to any man who killed Goliath ?

Is this a trick question Mr Dogspit
He offered Merab, but David ended up with Michal.

*** Rbi8 1 Samuel 18:17-20 ***

17 Finally Saul said to David: “Here is my oldest daughter Me´rab. She is the one that I shall give you as a wife. Only prove yourself a valiant person to me and fight the wars of the Living God.” But as for Saul, he said to himself: “Do not let my hand come to be upon him, but let the hand of the Phi·lis´tines come to be upon him.” 18 At this David said to Saul: “Who am I and who are my kinsfolk, my father’s family, in Israel, so that I should become son-in-law to the king?” 19 However, it came about that at the time for giving Me´rab, Saul’s daughter, to David, she herself had already been given to A´dri·el the Me·hol´ath·ite as a wife.

20 Now Mi´chal, Saul’s daughter, was in love with David, and they went reporting it to Saul, and the matter was to his liking

Correctamundo !

Thanks for the answer Patricia !