Protector was a title used by several alien races. The term "protector" was also used by Droxine to describe the filter masks supplied by the USS Enterprise to the Ardanan Troglytes. (TOS: "The Cloud Minders")
Colyus (or at least the hologram based on him) was a Yaderan Protector. He became Protector in the early 2360s. (DS9: "Shadowplay")
Protector was a title given to leaders in Kelemane's species. (VOY: "Blink of an Eye")