The Flash: 10 Best Characters Who Only Appeared In One Episode
4. Solovar
After The Flash introduced infamous DC villain Gorilla Grodd in its first season, it was only a matter of time before DC's other famous great ape would get his day in the sun.
Solovar appeared in a two-episode special (which both work as a singular episode story-wise) as the leader of the Earth-2 based Gorilla City. As fitting for a character of his presence and status, Keith David provided his distinct baritone voice to bring the gorilla leader to life.
Team Flash first encounters Solovar after Grodd captured the heroes during their search and rescue of Harry Wells from the simian settlement. The villainous ape informs Barry and company of Solovar's plans to invade Earth-1, and that he needed their help to stop this from happening.
Barry successfully subdues the would-be invader but it is revealed that Grodd intended to usurp Solovar and use his defeat to justify the inter-dimensional invasion. Later on, he was able to put aside his differences with Team Flash, help stop the Earth-1 assault and take back his role as leader of Gorilla.