Origin
Kelly was originally a normal chimpanzee who was owned by Katherine Hillard’s aunt; who was trying to teach her sign language. When Lord Zedd and Rita Repulsa caught wind that the Power Rangers were looking after the chimp, they took advantage of the situation and transformed Kelly into the monster who called itself the Sinister Simian.
Creation
Originally created for the Japanese show Ninja Sentai Kakuranger in 1994 as a minor villain only appearing in episode twenty-one as the monster known as Sarugami. When the episode was adapted for Mighty Morphin’ Power Rangers season three, episode twenty-eight, the character was drastically changed and renamed to Sinister Simian.
In Ninja Sentai Kakuranger was voiced by Ren Osugi and in Mighty Morphin’ Power Rangers voiced by Brianne Siddall.
TV Show
After being transformed into a monster by Rita and Zedd, Kelly caused indirect terror to the citizens of Angel Grove. Scared by the Power Rangers attempts to cure her of her monster form, Kelly fought against the Rangers in an act of self-defence, quickly overwhelming the Rangers as they tried not to harm her. When Kelly was transformed once again into a giant monster, Billy used a serum to change her back into a normal chimpanzee.
The Sinister Simian makes several more minor appearances throughout the Zordon Era, however, it is unknown as to how or why Kelly transformed back into her monster form.
Comic
Sinister Simian made a brief appearance in Power Rangers #4 as a background character in the Onyx Tavern.