|First appearance:||Book One|
|Armour level 1:||None|
|Armour level 2:||None|
|Armour level 3:||None|
|Ultimate level 1:||WarGrowlmon|
|Ultimate level 2:||None|
|Mega level 1:||Megidramon|
|Mega level 2:||Gallantmon|
|Mega level 3:||Gallantmon Crimson Mode|
Guilmon is Takato Matsuki's partner Digimon. He is unique in the way that he was created by Takato when he scanned a picture of Guilmon in his D-Arc.
Guilmon appears to be small when standing in his casual bent-over tyrannosaurus-rex like stance, but when standing up, he is actually the size of an adult human. Guilmon is a red dragon-like Reptile Digimon with yellow eyes, wing-like ears, a long and strong tail, and carries the black Digital Hazard symbol on his chest. Guilmon is muscular yet a little slender with big legs, perfect for fast running. On each of his strangely large hands Guilmon has paws, and three fingers with long claws; and on each foot, he has two clawed toes and a claw coming out from the heel. One very indistinct feature of Guilmon is the stripes and triangle patterns on certain parts of his body.
He was created by Takato after he did some drawings of his own Digimon and, using the D-Arc, they came to life. He is a virus-type Digimon, although his kindness can make him think as a data or vaccine-type.
He is a curious and naive Digimon, the youngest of the partners, and he has a strong love for bread. At first, he wasn't aware of the differences between humans and Digimon, calling his Tamer 'Takatomon', at times. Although he kicked this habit a few times, it returns in the fanfiction. Although he doesn't look like it, he is a playful and friendly Digimon, proving to be popular with Takato's classmates, seeing him as a real Digimon.
Despite being thought as childlike, he occasionally shows deep insight. This was shown when Takato didn't want Guilmon to digivolve for fear of changing Guilmon's personality. Guilmon answered back saying that Takato had also changed over time, although still being the same person.
Guilmon gets along well with Terriermon, Calumon and Renamon (although at first they thought of each other as enemies, plain and simple) and sometimes with Impmon (although he dismisses the fact). At first, Guilmon wasn't a very good listener (since he usually walked to the unknown or in other words towards Shinjuku, unaware that the humans didn't know what he was, and fought Renamon when he was told not to) but Guilmon started to admire Takato's determination and decided to obey him.
In addition, Guilmon is very powerful for a Rookie, taking in account that, at one point, he defeated a Champion level IceDevimon, while Renamon wasn't able to defeat him, even when she digivolved into Kyubimon. In the Dimensions books, we see a large increase of romantic feelings between Renamon and Guilmon, to the point that Takato planned out something to make the two kiss, and was successful. This relationship continued to progress, just as their human partners' relationship did. After Terriermon created a program to give digimon gender, a necessary addition once Yggsdrasil was destroyed, the two digimon actually created a digi-egg. The digi-egg eventually hatched into Rejimon, the partner of Rey (or "Rei") near the end of Book Six. Guilmon is a very enthusiastic parent, happy to play with his new daughter.
While Renamon does not seem to recall her previous lives with Harmony, Guilmon has demonstrated possessing a few scattered memories of his previous lives alongside Chaos, including fighting as Gallantmon against Sakuyamon.
Pyro Shpere: Guilmon spits a concentrated blast of fire from his mouth.
Rock Breaker: Guilmon hits his opponent with a huge amount of force, almost like he is throwing a rock at his opponent (This attack was used only once in the movie Runaway Locomon).