In his true form, Moo appears as a white and brown hideous giant Dragon as the fur on the edge has a red tip.
In his weaker form, Moo appears as a combination between his monster form and his human host and is taller than General Durahan. He wears a golden suit of armor with a baddie crest on his front cape and belt, he wears a golden horned helmet and a long black and red fur cape as the fur on his long cape resembles the fur from his true form. His face is covered in a shadow hue and red eyes.
As Moo's final form where he fuses with General Durahan as Ruby Knight, his armor is the same as his weaker form but the color is now bright red.
History EditAs told by Monol, Moo was the ultimate genetically-engineered weapon in the great war of ancient times. His dark powers eventually grew too powerful to be controlled by his scientists, and when he learned how powerful he was he stopped working for either side and began creating his own army with his ability to transform good monsters into his evil baddie servants. The surviving scientists created a second creature capable of defeating Moo, calling it the Phoenix. They battled, but proved to be too closely matched. Realizing that they had no other choice, the scientists used the unlocking technology in a way they never had before--to separate Moo and the Phoenix from their bodies. Moo's soul became locked in a Mystery Disk in his castle, along with the Mystery Disks of some of his most trusted troops.
Centuries later, Holly's father was banished from his village and went in search of the Phoenix without the aid of the Magic Stone. He eventually found Moo's castle, where he unintentionally unlocked Moo's soul. The malevolent spirit took over his body, creating a human/monster hybrid version of Moo. He took five new generals, calling them the Big Bad Four (and General Durahan) and began a conquest on the world once again. Some areas were completely taken over, and the humans and peaceful monsters there were either converted to his ways, killed, or made to be slaves. Each of his generals ruled a section of the continent he took over, while Durahan acted as a roving agent. Moo used his floating castle to travel in search of his ancient body, and after reclaiming the Magic Stone from Holly, was finally able to locate it.Though he is mentioned several times in the first six episodes, Moo doesn't appear in person until the seventh episode, and in Episode 13 he easily defeats Tiger, Hare, Mocchi, Suezo, Golem and Genki, taking Holly captive. Through the combined efforts of the Searchers, the Pirate Dragons and a littler interference from Pixie, Holly and the Magic Stone are rescued, but not before Moo learns the location of his body. Moo flies to the North in his Castle and orders his minions to begin an excavation so that he can find it, but after uncovering it he realizes he cannot merge with it. Finally they find the machine that separated his body and soul and use it to fuse him back together. He begins to battle the Searchers, but when the sun comes up, he begins to burn and weaken. Only then does he realize he needs the Magic Stone again to complete his transformation.
By the time he has merged with his body, Pixie has switched sides and his three other lieutenants have been killed, so he sends General Durahan to do his work.
After Durahan's servants are defeated, he betrays Moo and takes the Magic Stone. Unfortunately the betrayal doesn't end there. Durahan's sidekick Lilim reveals she has been loyal to Moo all along, and tries to double cross him. Captain Weed ends up with the stone, who returns it to Moo, while Lilim and Durahan go down in his burning ship.
Moo perfects his body and then turns his attention to destroying the Searchers, mortally wounding Pixie in the process. But unfortunately, he realizes he has absorbed too much hate over the years and it drives him insane. He rampages, destroying everything including his castle and his troops. Genki is able to use his courage to summon the Phoenix, which is really Mocchi (the Phoenix's courage), Suezo (Phoenix's pride), Golem (Phoenix's kindness), Tiger (the Phoenix's anger), and Hare (Phoenix's intelligence). They fuse together into the Phoenix 's frozen body, which then fights Moo. They destroy each other, exploding in a huge ball of light.
Though his body was destroyed, Moo's soul and Holly's father's body become sealed inside a disc together. When Genki returns to the monster world, Holly and Mocchi meet up with him and tell him about the disc. After reassembling the old gang, the crew decided to find a shrine and free Holly's father, and very nearly release Moo in the process. However, Durahan (who survived his crash) was searching for the disc so he could absorb Moo's soul and use its power as his own. His followers eventually ambush the gang and steal the disc, along with the Magic Stone.Though he succeeds in his plan, Moo turns out to be too powerful just as the Searchers interferes, and takes over Durahan completely, also absorbing his henchmen to become a massive Ruby Knight.
Even though the Searchers fight valliantly, they have no effect on Ruby Knight until Holly's father interferes. He regains his memory of his years being tormented by that soul, and shows Durahan how to overcome the darkness. Genki, Holly, Holly's father, Durahan, Poison, Mum Mew, Gobi, and Weed merge with the Phoenix, empowering him to charge into Moo and destroy him forever.
Moo has a vast number of followers called Baddies, which notable members are:
- Big Bad Four
- General Durahan
- Seed Sisters
- Weeds & Captain Weed
- Dinos & Captain Dino
- Worm troops
- Moo was voiced by Paul Dobson,who presumably voiced Holly's father as well.
- Moo appeared as a ??? monster in Monster Rancher 2 only available on the CD Beck: Mellow Gold.
- Moo is similar to Darth Vader from Star Wars, seeing as they both have a similar appearance, deep voices and, in a way, Moo is Holly's father.
- Two of the crucial episodes to Moo's quest for his original body were skipped by the Fox channel. Tiger's Battle with Destiny, the episode where Gray Wolf was defeated, is also the episode where Moo finds his original body, and Battle with the Big Bad Four, the episode where Naga was defeated, is the also episode where Moo merges with his original body.
- Despite how evil and powerful he is, and how many people are frightened of him, the name is Moo may not sound very intimidating to some, as it is both phonetically and gramatically similar to the sound a cow makes in English. However, this is a play on the Japanese word for void, meaning "nothing".
- Zevion, a dark monster that appears in Monster Rancher 4, is Moo's spiritual successor, as both have an army of evil monsters (Baddies for Moo and Dark Ones for Zevion). They both share a color scheme as well.
- The main villian of Monster Farm Lagoon is Moo once again, and this time, several level bosses are simply monsters (such as Tiger, Kikimo, and something called "Larva Mode," which looks alot like the dragon manifestation of Moo's soul) taken over by Moo's soul. However, Moo's true form in this game has 4 wings instead 2.
- Interestingly enough, Moo has the exact same color scheme as the Ripper from Monster Rancher 4. Perhaps a sub-type?
- Moo's defeat is somewhat reminiscent with Izanami's defeat in Persona 4, as both of them destroyed by single powerful attack.