Balok was the commander of the First Federation vessel Fesarius, which encountered the Enterprise in the Star Trek: TOS episode "The Corbomite Maneuver".
He was portrayed by Clint Howard.
Encounter with the Enterprise
The Fesarius first confronted the Enterprise after the latter vessel destroyed a First Federation navigation buoy, which was emitting harmful levels of radiation to the Enterprise crew. Balok interpreted this action as hostile and threatened retaliation by destroying the Enterprise, offering the crew 10 minutes to make any spiritual preparations they wished before death.
The Corbomite Gambit
In response to Balok's threats, Captain Kirk quickly invented a bluff by describing a device known as "corbomite", which would activate a material of the same name to cast an equally powerful reflective attack destroying the attacker as much as the Enterprise itself. In response, Balok did not engage in his attack after the appointed time had elapsed, but instead decided to tow the Enterprise to a planet for resettlement of the crew and the destruction of the Enterprise itself.
The True Balok Revealed
The towing operation put a severe strain on the tiny command ship dispatched from the Fesarius. When all systems were in danger of failing, Kirk, along with Dr. McCoy and Lt. Bailey, went over to investigate.
It was discovered that the intimidating face they thought was the face of Balok was nothing more than a mechanical puppet, and that the real Balok had an appearance resembling a human child. Balok had used the puppet in order to elicit the intimidated response from his adversaries. Aboard the command ship, Balok and the landing party reconciled over glasses of Tranya, sharing in the mutual pride each commanding offer felt for his vessel.