Dragon Ogres/Ogors are a bunch of chaos worshipping, half-man half-dragon centaur like monsters in Warhammer Fantasy and Age of Sigmar. They are huge, terrifying monsters that eat lightning and crap thunder...and are also exceptionally lazy. No really, they are giant creatures that sleep 24/7 and they only wake up when there's a big thunderstorm going on. This would make them probably the laziest chaos worshipers next to the Nurgle's lot, except they would get shit done and wreak havoc on the world if they did. Like the dragons, they existed way before the Old Ones came, actually being at war with dragons before then.
For those of you who know their mythology, they're a reference to the Giants of Greek Myth who were mothered by Gaia and fathered by Tartarus to make war upon Zeus and co. for imprisoning the Titans before them. Said giants were noted to have ugly humanoid upper bodies and monstrous reptilian lower bodies like their siblings Typhon and Echidna.
Dragon Ogres are immune to any attack that contains electricity in it, such that it even gives them power. The monsters often bathe in lightning before battle in order to store the energy and unleash it like a 'Lore of Heaven' spell. Like a centaur, they have normal human upper body and the body of a monster below. Having four legs gives them the speed advantage against other large creatures like giants (slow two leg walkers lol) while holding big, two-handed large weapon for battle. They have scaly skins which makes them resilient to any range attack like arrows from hurting them. They are also known to be very big, like, REALLY FUCKING BIG. They are so big that some people called them the mountain god and worship them. They gain their large body through aging. They are also known to be immortal due to the pact they made with chaos long ago in exchange for servitude (this also made them completely infertile).
Ever since the pact was made, dragon ogres has lived in a life which they assume to be an eternal bondage. They have no need for food nor there's any need of survival for them so they just went to sleep. They were hoping for some sort of apocalypse that would end their boring torment, which they probably got what they wanted.
There's two type of dragon ogres, the regular one and the the larger one called Shaggoth, who are just much older and larger dragon ogres.
Also, they are not related to the OGRES despite having named "dragon ogres" in their name (the adventurers probably compare them so as a way to capture their brutality in combat). Then again Dragon Ogres predates any of the old one creation. Thanks to the ignorant manlings slapped the name on them without knowing the whole story, we are now stuck with it.
Known unique Dragon Ogre
Krakanrok the Black - Big daddy of all the dragon ogres, the oldest of his kind. He was the one made the pact with the chaos gods long ago. Archaon met him while doing his quest for slayer of the kings (the demonic sword that contained a greater demon known as U'zuhl) where the weapon is clasped to the sleeping Krakanrok's chest. Archaon call his strongest companion to pry one of the dragon ogre's claw but the sword's car/demon alarm went off. Krakanrok is so big and frightening that not even Archaon wants to wake up the beast so he took the sword and use it to kill the companion that was holding Krakanrok's claw in order to sating the sword's thirst for blood. Krakanrok was foreshadowed that he would be awoken from the loud thunderstorm during the End Times, but he was never mentioned so let's just assume he died in his sleep when the chaos gods destroy the warhammer world. As of Age of Sigmar turns out he did not die at all. The Beasts of Chaos book states that a Dragon Ogor Shaggoth the size of a mountain survived the end of the world and once again spread out his progeny. The book later states this Progenitor is once again Krakanrok.
Kholek Suneater - Krakanrok's son. He was there when daddy offered their entire race to the chaos gods. Kholek played a role in that, and since that day he's constantly followed by a thunderstorm. Was seen during Asavar Kul's (the fourth Everchosen) invasion to Kislev where he single handily broke down Kislev's walls with his TOTALLY NOT THAT THUNDER HAMMER called "The Starcrusher", destroyed the Gryphon Legion that was flank charging the chaos armies and smashed many temples inside the city. During the End times, he went out of control that Archaon had to sent the newly arrived Settra to deal with him. They fought in such super saiyan scale battle that it leveled the forest trees. Settra wins and cut down Kholek's gigantic head and drag it back near Archaon's feet. He appears in as a Legendary Lord for the Warriors of Chaos in Total Warhammer, infamous for his capacity to stack up ward save and missile resistance with items along with what's provided in his skill tree to make him nigh-invincible.
Dragon Ogre Chaos Champions
Way back when introduced in Realms of Chaos, it was possible for Dragon Ogres to claim the title of Chaos Champion and lead both their own warbands on the Path to Glory and armies in Warhammer Fantasy. These subsequently vanished from the canon.