Canonically we know only what was shown during the course of Star Trek V: The Final Frontier, and nothing more. The being in question was a powerful entity capable of manipulating and deceiving others, but no other information about its origins are shown. There is no indication that it is directly related to any of the other "god-like" beings encountered over the course of the subsequent series.
Non-canonically, according to the novel Q-strike by Greg Cox, the entity in question was a being known as "The One" and was brought into the universe by Q and one of his associates, along with Gorgan and the Beta XII-A Entity. The Q continuum banished The One beyond the galactic barrier after the creature committed various atrocities.