UG the Uglithug was the chief of the Uglithug tribe and the father of Tantrum O'Ugerly Hotshot. UG also ruled the Uglithug slavelands prior to the Second Dragon War. He was also known for sending many men on impossible tasks to win Tantrum's hand in marriage. UG was killed by the Dragon Guardians of Tomorrow a few days before the Doomsday of Yule by attempting to trick the Druid Guardian into crowing him King of the Wilderwest.
When the Hooligans camp on the Bay of the Broken Heart during their search for Camicazi, UG sneaks up on them while they are sleeping. UG is angry with the Hooligans because he believes that they are trying to claim his lands when he sees the Throne of the Wilderwest on his shore. Though UG then says that was a joke, he is actually upset over the fact that a Hooligan man has been sending his daughter Tantrum O'Ugerly love letters along with a Berk Bog Rose (a type of thorny rose that grows only on Berk). UG tellls Stoick that if the man doesn't come forward he will kill every not-married Hooligan boy and man. Hiccup deduces that it was Fishlegs who sent the letters. Because of this as well as knowing that only a Chief's son can send another chief's daughter love letters without being killed Hiccup lies and says that he is the one that has been sending his daughter the letters so UG sends him on an impossible mission to Berserk to collect honey from the bees there.
It was revealed that the Excellinor the Witch kidnapped UG, and imprisoned him in the old cabinet. Excellinor kept defeating him at chess, and threatened to kill him later, in revenge for her being imprisoned for twenty years. When UG and Stoick were rescued by Hiccup, UG ran away with the terrified Flashburn and left the Swordfighting school, never to be seen
Ug attempts to trick the Druid Guardian of the Singing Sands into crowning him king. All of those who come to be King must bring with them The King's Lost Things to prove that they are indeed the one chosen to be King. UG's Lost Things are fakes, including a tooth free Trotterdragon that UG maliciously defanged. As punishment, the Druid releases from beneath the sands the other fearsome Guardians, who carry UG and his men into the sky and tear them to pieces, thus killing the Uglithug chief.
UG wanted his daughter to be married to a person of royal blood. However this may not be strictly true as when he sends his daughters fiancés on impossible tasks (which Vikings must complete in order to be married) he lets the nearby Berserk tribe know and the Fiancés are always captured.
When UG finds out that a member of the Hooligan tribe has been sending love letters to Tantrum he demands that the person own up and be killed (unless the person was of royal blood) or all the unmarried young men in the Hooligan tribe will be killed.
After being released from the Witch's Hut in Flashburn's School of Fighting, UG runs off, never to be seen again. Or so the book says. In truth, UG manages to make it to the Singing Sands of Tomorrow, where the Druid Guardian awaits them. Despite his blindfold, the old man can tell that the Lost Things, which the true king must carry, are just fakes, and unleashes the other Guardians from down below to kill UG and his whole army of men.
There is little physical description of UG in the book. Hiccup described him as having a large stomach, like that of a torpedo. He wore a Viking helmet with stag horns, and always smoked a cigar.
There has been only one illustration of UG, unfortunately, the illustration only shows the shape of his body in the dark. It is also shown in the picture that he has a silver beard.
Stormfly is Camicazi's mood-dragon which UG claims Camicazi originally stole from him, although Camicazi denies this. Given the propensity for lying all three involved parties have, Stormfly's true origin will probably never be known. UG captured her in How to Break a Dragon's Heart, but Stormfly showed loyalty to Camicazi and claims to have bitten "that rude Uglithug" many, many times.
- Ug is the only character in the series seen using a cigar.