He is a minion of Skeletor and makes only one appearance, in the early episode "She-Demon of Phantos". He appears to be a cyborg warrior, wearing a tight metal mask with spikes over the head, with a strong metal fist at the end of his extra-long right arm, which is capable of extending. His arm possesses strength powerful enough to rival that of He-Man.
In Strongarm's singular appearance on the cartoon series in 1983, he fills the role of Skeletor's main minion in his invasion of the moon of Phantos, on which Skeletor enslaves Queen Elmora. Strongarm is portrayed as a powerful and responsible minion, of greater intelligence and capability than most of Skeletor's warriors. His main accomplishment in the episode is his success in trapping He-Man, by using the power of his fist to shake the ground, causing He-Man to stumble back into a Photanium body cell which entraps him. He is also able to extend his arm, which enables him to grip onto objects and swing long distances.
Despite the implication that he is one of Skeletor's more powerful minions, Strongarm makes no further appearances throughout the series. This is most likely because he was one of the few characters from the show not to have an accompanying action figure in Mattel's toy line upon which the show was based. Given that he bears a notable resemblance in power to the character of Fisto, whose toy was released the following year, it is possible that he may have been an early prototype character originated from the concept which later spawned Fisto. Fisto's rival in the toy line, Jitsu, with a similar design and power, appears in the cartoon series at the same stage as Strongarm, in prototype form under the name of Chopper. So it would seem likely that Mattel was experimenting with designs for characters based around the concept of having one extra-large, powerful arm, at this stage, and Strongarm, like Chopper/Jitsu, is featured in the series to promote a possible upcoming figure. Although in Strongarm's case, his character and design was clearly abandoned in the favor of the heroic character of Fisto. Another theory is that Strongarm was purely Filmation's own creation, as with a number of other villains that appeared through the show's run.