How many of the true slaadi forms manifested in the earliest days of Chaos cannot be known. Most of the earliest ones probably immediately dissolved into the soupy chaos from which they spawned.
The oldest known was
Ssendam, a giant golden oozelike being with a complex - and utterly mad - brain visible within. Some claim she spawned the rest of the slaad race - not physically, from from her deranged dreams.
Only slightly younger, and rarely spoken of today, was the true slaad remembered only as the
Queen of Chaos. The Queen begun a war with a rigidly lawful race of the Elemental Plane of Air; this would continue for eons, leaving her with time for little else. The Queen had an obese humanoid form with a lower body like a mawed squid. Ultimately she would leave Limbo entirely to join her half-tanar'ri, half-true slaad offspring in the Abyss, the so-called spyder-fiends.
The last surviving member of the true slaadi made perhaps the greatest impact on the later history of the slaadi,
Ygorl. Ygorl resembled a humanoid froglike creature made of utter blackness. It was Ygorl who created a stone that would limit future generations of slaadi to a froglike form similar to his own; he took this stone to Ssendam and convinced her that the soul of the slaad race would only be safe if she hid it within; in her paranoia, she invested the object with the racial soul, causing them to be fertile only if they visit it once a year. She still guards it, though she no longer remembers why.
The latter-day Lords of Chaos have thus all inherited Ygorl's froglike form, at least to some extent. They have evolved to this new state from black slaadi, mostly, except Chourst, who was the first of the white slaadi.
Chourst was the first of the modern slaad race to evolve into the status of Lord of Chaos. Chourst is a slaad of brilliant white, and ever since its ascension the two greatest slaad castes have resembled Chourst and Ygorl. Chourst represents pure randomness, and it is the only Lord of Chaos to have fought the One and Prime and lived. Actually fighting Primus wasn't as impressive as making it through all of the modron hierarch's defenses and back out again, but all of the modrons' carefully-laid plans seemed to dissolve to nothing in Chourst's tide of improbable coincidences. Some say Primus was actually killed in the conflict (quickly replaced by a secundus), while others say at the last minute Chourst grew bored with the adventure and left of its own accord.
Still younger is
Bazim-Gorag, the two-headed Lord of Fire. Bazim-Gorag originally represented fire in all of its chaotic manifestations, positive and negative - its radiant, ever-changing glow, its life-preserving heat, its ability to shape metal and stone, its cleansing properties, its capacity for both destruction and renewal. Somehow, however, one of Bazim-Gorag's two personalities was corrupted by evil (some say by the Queen of Chaos, who was still at the time recruiting for her seemingly endless war), and the conflict between its evil and neutral aspects made Bazim-Gorag even more dangerous than it would have been if it had been merely evil. Ygorl debated with Ssendam's many mad personalities, both lucid and not, the merits of destroying Bazim-Gorag, but they elected not to. Eons later, Bazim-Gorag was somehow bound on the Material Plane.
Wartle is the next oldest Lord of Chaos, the Lord of Formlessness. Wartle represents utter nothingness, and in its presence even the Spawning Stone began to dissolve. Wartle was ultimately banished from Limbo.
Youngest of all is
Rennbuu, Lord of Colors. Rennbuu's wild mane of white hair makes it stand out from other slaadi, though it shares Ygorl's froglike shape. Rennbuu represents a great threat to many slaadi, having the power to change their caste by changing their colors, but this seems only to amuse the greatest of slaadkind.
Still younger is the black slaad
Sorel, who Ygorl is grooming to be Lord of Anarchy. Most of the actual training is being done by Ygorl's brass dragon mount, Shkiv, a member (and possibly the founder of) the Revolutionary League, as Ygorl has many other things on its mind.