Simian is an Arachnichimp, and is one of the many antagonists in the Ben 10 franchise.
Being an Arachnichimp, Simian bears a strong resemblance to Spidermonkey. However, he has yellow eyes instead of green, also lacking an Omnitrix symbol, and stripes on his tail.
In Ben 10: Omniverse, he still looks like Spidermonkey, but now has black eyes and yellow pupils. He now has a flipped-up, white hairstyle. In addition, he wears clothing now, notably a pink shirt. He also now has two white stripes on his tail. In Collect This, Simian is shown wearing a wig identical to Gwen's hair, a purple plaid skirt, and Kevin's blue wholesters.
Ben 10: Alien Force
Simian appeared for the first time in Birds of a Feather, where, coming on Earth, he met Spidermonkey, Gwen and Kevin being attacked by a group of DNAliens. Mistaking Spidermonkey for a true Arachnichimp, Simian interfered in the fight and forced the DNAliens to leave, saving the group. When learning he had actually saved "Ben Tennyson" and his team, he declined their offer to join their team to fight DNAliens, stating he couldn't. He also said that he didn't know anything about DNAliens.
Later however, Ben surprised him when he was stealing equipment from a cryogenics lab. Goop] helped him to escape, but asked for an explanation. Simian then replied he was the Prince of Aranhaschimmia and to prove he was a valuable king, he had to get and bring back to his planet a crystal from a base on Earth's moon. Feeling empathy for him, Ben decided to help him and convinced reluctant Gwen and Kevin to come too.
Arriving on the moon, the group successfully passed through the base's defenses, even being crushed before spraying the acid on the floor, but Ben started having doubts about Simian's motivations when he asked him to attack Lu, the harmless guard of the base, and tried to kill him himself when Ben refused. It was eventually revealed that Simian had lied to Ben, and was actually a mercenary hired by a Highbreed to steal the crystal, which was the power source of a communication base needed by the Plumbers to protect Earth from the inevitable Highbreed invasion. He pushed Kevin aside when he made his escape. Later, while he was getting to the ship, he attacked Gwen.
Ben later stated that he fully doubted Simian when he mentioned the DNAlien's acid, because Simian said he had no idea who DNAliens were.
When bringing the crystal back to his client, Simian realized too late that Ben had replaced the crystal inside the container with a DNAlien ear cleaner filled with worthless, but powerful acid. Thinking this was a joke from Simian, the Highbreed chased after Simian and seemingly attacks him with the acid. However, the Highbreed changed his mind to the Highbreed ships and lock him up.
Ben 10: Ultimate Alien
Simian was imprisoned by the Highbreed, but he escaped and returned in Simian Says after they encountered a problem using a Xenocyte. He then headed to Aranhaschimmia where he sold the Xenocyte to Mizaru. However, the Xenocyte broke loose of the container and attacked Mizaru, forcing Simian to plead for Ben's help as later the Arachnichimps were being converted into DNAliens, though they slightly look different than humans infected with Xenocytes. At first, the group was reluctant but agreed to aid him. After saving all the Arachnichimps and defeated Mizaru, Ben commented that Simian can be a prince, noticing him destroying the last Xenocyte.
At the end of the episode, Simian sold a DNA ray gun he found earlier to Emperor Milleous, revealing he has returned to his criminal ways (thus proving that Kevin was right about him).
Ben 10: Omniverse
Simian returns in Collect This and sold out the Earth in Ben's name. However, his plan goes sour as he is collected by Collectimus as one of the Gwevin characters. At present, he is now trapped inside one of his collector cards.
Powers and Abilities
Like all Arachnichimps, Simian has enhanced agility, can stick to walls, spin webs, shoot webs from his tail.
Simian is very skilled in hand-to-hand combat able to defeat multiple DNAliens in rapid succession with ease.