The Maggoth Lords or the Maggot Riders are the three Chaos Champions of Nurgle, Orghotts Daemonspew, Bloab Rotspawned, and Morbidex Twiceborn, introduced in the second End Times book. The three of them ruled over Icehorn Peak, a realm located in the Chaos Wastes. Their namesake are the hideous monsters known as Pox Maggoths, which they ride as a sign of Nurgle's special favor. They survived the transition to Age of Sigmar alongside The Glottkin and Gutrot Spume. In both settings, they are the Glottkin's chief lieutenants.
The leader of the group, and the de facto ruler of Icehorn Peak. Distinguishing him from other chaos characters, he's half-daemon, having been born from the union of a Great Unclean One and a human witch (don't think how that would work for the sake of your sanity). He's also old as fuck, having been alive before his companions and having participated in the Battle of Kislev's Gates during the Great War Against Chaos.
The fact that he's only half daemon angers him to no end, as he wishes to become a true daemon and obtain what he perceives to be his rightful heritage. He's tried many things to become a daemon, from literally walking to the Garden of Nurgle, which was always just out reach for him, and it was during one of these journeys he aquired his Rotaxes, to attempting to contract Nurgle's Rot so that he could at least turn into a Plaguebearer, but to no awail. Since then he's been trying to prove himself to Nurgle and become a Daemon Prince.
He died when Karl Franz ascended, being burnt to ash by the magic of the Incarnate of Heavens.
On the Tabletop
Bloab was originally your regular northman warrior who worshipped Nurgle, albeit one with a habit of torturing small beings. Nurgle, loving all beings no matter what and taking offense that he would torture insects rather than kill opposing champions, decided to teach the warrior a lesson. After one of his hunting/torture trips, he fell asleep in a cave whilst Morrslieb was full. From there, a swarm of daemonflies flew down to his cave and laid their eggs inside his body before flying away.
The next morning, he awoke in pain, as the larvae ate his insides slowly until he was naught but his toughened skin. Nurgle however was merciful to him, and used his powers to ensure his survival, and bound the daemonflies to him. Since then, he has repented his former sins and has gained high favor in the eyes of Nurgle.
He was reincarnated in Age of Sigmar, only to be killed again by the former Nurglite Stormcast Eternal Tornus the Redeemed. The other Maggoth Riders were able to ressurect him by throwing a single maggot into a pit full of captive ogres and allowing it to feast on their flesh and multiply, for as long as the swarm lives, so too shall Bloab.
On the Tabletop
Originally called Morbidex Fireborn, for he was born as his village was burnt to the ground and he was disfigured by the flames. As he grew up and learned more about the Chaos Gods, he learnt that Tzeentch was associated with the fires of change, and somehow became convinced that Tzeentch himself had disfigured him and that he would take revenge for it. His tribes shamans, of course, told him how fucking stupid he was thinking that Tzeentch would personally burn his village and him in process, but he didn't listen to them and set off on journey to gain the aid of Nurgle.
He has been recently resurrected in Age of Sigmar by Nurgle (probably).
As he travelled further and further north, the Garden of Nurgle came to him, as the realm spread to the lands he was travelling. It was during traversing these lands, whilst climbing a sheer mountainside, that an avalanche of Nurglings took him down to the bottom of the mountain. He woke up, trapped beneath the cute little boils and their liquids, and desperately trying to dig his way out. After some time, one of the nurglings came to him and asked him a child's riddle, and after ignoring him for some time, Morbidex gave the correct answer, causing the nurgling to help him get out. The process repeated itself several times, with him failing to answer three of the riddles, giving him his distended stomach, a tentacle sprouting from his left elbow, and turning face and voice to that of a nurgling. Suffering through the transformations, and with the help of the nurglings, he clawed his way out of the pile, and earned the respect of the daemon-mites.
He died off-screen during The End Times, getting killed by Vilitch the Curseling after attacking the latter due to Morbidex's hatred of all things Tzeentchian.