Grebnedlog is the main antagonist of the Star Trek: The Next Generation episode "Samaritan Snare".
He was portrayed by the late Christopher Collins, who was the original voice of Mr. Burns in The Simpsons, Starscream in The Transformers and Cobra Commander in G.I. Joe.
Grebnedlog was the captain of the Pakled ship Mondor. His people had stolen their technology and thus had very little idea how to operate, maintain or repair it. When his ship broke down, he sent out a distress call which was picked up by the Enterprise, with Riker in temporary command. Lulled into a sense of security by Grebnedlog's simple-minded behaviour, in which he repeatedly mentioned "searching for things to make us go", Riker sent chief engineer Lieutenant Geordi LaForge across to carry out repairs. However, there proved to be too many things wrong with the ship, so the Enterprise prepared to take it in tow.
At that point, Grebnedlog stunned Geordi with his own phaser and took him hostage. Contacting the Enterprise, he demanded the ship's computer banks, shooting Geordi again to make his point in a way that threatened serious injury. The Enterprise crew refused to surrender their computer and indicated they considered Geordi expendable, also acting as though he was a weapons specialist. This intrigued Grebnedlog, who ordered Geordi to update their weapons systems.
The Enterprise pretended to attack the Pakled ship, acting as though they were prepared to kill Geordi with everyone else on board to give away information. A timed plan saw Geordi take the Pakleds' weapon systems offline at the same time the Enterprise vented plasma, pretending they had been disabled by a "crimson force field". Defeated, Grebnedlog lowered the shields and allowed the Enterprise to beam Geordi aboard and depart.