The Simians were a race of ape-like aliens which came from Black Hole Planet 3. As their planet was getting sucked into a black whole, they intended to invade Terra to have a new home. They intended to uses Titanosaurus who was psychically-linked with a human boy named Tristan. The last group of Simians were killed on their moon base by SpaceGodzilla.
The Simians are humanoid in body structure and the same size as a human. They are ape-like in appearance with their faces almost resembling those of an Terrian ape. The skin on their faces is pink and wrinkled. Their eyes are yellow and the hair on their heads is grey in colour and his goes straight up.
Like the Cryogs, the Simians are capable of shift-shaping as they can take on the appearance of humans.
The Simian race lived peacefully until they were caught up in The Thouasand Year War as the joined forces with the Kilaaks and the Millenians against the Xilians and the Nebulans, however the Simians were forced to back out half way through to avoid major casualties and loss of resources, as a result the Simians survived the war.
Soon afterwards, a black hole formed near their sector of the galaxy which began to suck in the first two planets in their solar system. With their home world slowly being absorbed by the black hole, the Simians set up a moon base on their moon. In need of a new planet, they intended to invade Terra. Their leader Mugal came to Terra and disguise himself as the head master of a academy for young psychic humans who are capable of communicating with Kaiju.
Post Trilopod War Arc
In 2015 at Kyoto, Mugal is at the psychic academy introducing the newest members (one of them being Tristan) and explains that the academy is to develop the abilities of the psychics so they can perform a psychic link with the kaiju to prevent then from attacking cities, similar to how one of the academy staff Miki Saegusa could perform a link with Godzilla. Mugal performs a series of tests to see if Tristan can connect with a kaiju. During another test, Mugal uses a device to push Tristan further and through his fear and pain is able have Tristan form a connection with Titanosaurus but the experiment is interrupted by Miki who doesn't believe the experiment is the right thing for Tristan. Later that day, Mugal and Miki discover that Tristan used his power to create an explosion at the academy and travel to his home at fast speeds. At Tristan's home, several Simian agents kidnap Tristan's parents, just as both Tristan and Titansaurus arrive. As Tristan is focused on Titanosaurus, the Simian agents incapacitate him, Titanosaurus is about to attacking the aliens for harming Tristan but a Simian ship arrives and abducts the Earth Defender. Meanwhile at the academy, Mugal tries to confront Miki over Tristans absence, hiding the fact he knows what has happened to the boy.
Later the Simians managed to bring Titanosaurus and Tristan to their moon base, they keep Titanosaurus chained in a tank of water and keep Tristan in their lab. The aliens prepare for their invasion of Terra as they build their MechaGodzilla drones similar those of the Cryog and the prepare their armada. In the lab, Mugal talks to a retrained Tristan telling him that he passed out from stress after he connected with Titanosaurus. Tristan asks to see Miki and Mugal sends a Simian disguised as Miki to convince Tristan they are not a threat. The Simians intend to uses Tristan and Titanosaurus as part of their invasion of Terra. Mugal states that Trsitan might be powerful enough to penetrate their alien minds so intend to keep him sedated until they reach Terra.
About a month later, the Simian are still observing both Titanosaurus and Tristan. They see there is little activity coming from Titanosaurus due to his depressed state of believing the Earth Defenders abandoned him, Mugal believes that Titansaurus and Tristan's connection are not strong enough. Mugal observes his home planet getting sucked up into the black whole as he becomes more determined to begin the invasion as its only a matter of weeks until the planet and eventually the moon base. Suddenly the Simians pick up an object coming towards their base and Mugal orders to have it shot down but the object lands at the base. Simian soldiers and tanks go towards the object which is revealed to be SpaceGodzilla. The Simian soldiers and vehicles fire at the crystalline saurian but have not affect and SpaceGodzilla fires his Corona Beam at the Simian forces, destroying them. Mugal then sends out their only working MechaGodzilla but the machine is destroyed by the space kaiju and sent towards the Simian lab building, destroying it and killing the remaining Simians and Tristan.
Shape-shifting: Like the Cryog the Simians are genetically capable of shift-shaping which they can uses to mimic or disguise themselves as humans.
Advanced Technology: The Simians posses advanced technology. With this technology they were capable of space travel and building robots like the MechaGodzillas.