Omri (Omriyah, Hebrew: "Yahweh is my life") was king of Israel and father of Ahab. Albright has dated his reign to 876 - 869 BC, while Thiele offers the dates 885 - 874 BC. He was "commander of the army" for Elah when Zimri slew Elah and made himself king. The troops at Gibbethon decided instead to elect Omri as king, and he led them to Tirzah where they trapped Zimri in the royal palace, and where Zimri died (1 Kings 16:15-19).
Although Zimri was eliminated, "half of the people" supported Tibni in opposition to Omri. It required Omri some years to subdue Tibni and at last proclaim himself undisputed king of Israel in the 21st year of Asa, king of Judah (1 Kings 16:21-23).
Because Omri was not a devout follower of Yahweh, the author of the Book of Kings minimized his accomplishments. While the author acknowledges Omri founded his new capital Samaria on a hill he bought from Shemer (16:24), he omits any mention of the widespread public construction both Omri and his son Ahab commissioned during their reigns. Israel Finkelstein and his student Norma Franklin have identified monumental construction at Samaria, Jezreel, Megiddo and Hazor similar in design and construction, including 12 sets of mason marks shared between the archeological sites.
Omri's rule over Israel was secure enough that he could bequeath his kingdom to Ahab, thus founding a new dynasty (sometimes called the Omrides), and his descendants not only ruled over the kingdom of Israel for the next 40 years, but also briefly over Judah. He was significant enough that his name is mentioned on a stele erected by Mesha, king of Moab, who records his victory over a son of Omri -- but omits the son's name.