Cleveland Booker IV was an alias used by a Human courier who served as mentor to Tareckx in the 32nd century.
This Cleveland Booker was the fourth courier to operate under that alias. He (and the Cleveland Bookers who preceded him) developed a reputation for trustworthiness. (DIS: "Species Ten-C")
He had a daughter, Malinne, who later became a courier herself and changed her name to Moll. (DIS: "Under the Twin Moons")
When this Cleveland Booker retired, Tareckx adopted his name as an inspiration and motivation for himself to live up to it. (DIS: "That Hope Is You, Part 2", "Species Ten-C")
He died sometime before 3188. (DIS: "Mirrors")
This character was only mentioned in dialogue.