There are only three Shadows known by name. Ler Rhan and Black Ferah are "generals" in the service of Bael'Zharon. They are extremely powerful entities that do not seem to fully exist in our world. Instead, they send aspects of themselves into Dereth.
You hear a childish voice say, "Long ago there were five, but now there are three. They will have their revenge."
The Fourth Sending of Darkness
Ilservian's surviving friends became corporeal once more and raised the Thorns, using them to alter the patterns of magic in the world. Ferah, by now called Black Ferah, and Ler Rhan attacked the Isparian population and kidnapped some of them for individual trials. 
The Shadows launched their invasion during the Thorns of the Hopeslayer patch. Their armies poured into the Direlands under the leadership of general Black Ferah. After being defeated a few times, she moved her command post into one of the Shadow Spires where she was overwhelmed after a coordinated attack of the Isparians.
The invasion of Ler Rhan's forces started in A'mun Desert. Unlike Ferah, he elected to directly establish his headquarters in the Spires. After he was slain there, he moved on to the plains in the Aluvian-settled regions of Dereth. Again, he was tracked and defeated. Once more he moved, into the Spire found in the Blackmire Swamp. Once more he fell.
Ler Rhan's forces invested Anadil's garrison at the Fenmalain Vestibule, but the battle ends indecisive, partly due because Isin Dule withheld his forces. Before any action could be taken by the divided Shadows, the Isparians interfered again and destroyed all three of the Vault Crystals.
To overcome this, Ferah and Ler Rhan assumed human form once more and contacted the Isparians they abducted and tested before. Together with one of them, Vidorian, they swept into the dungeon, drove the defenders back and shattered the Shard of the Herald. With a shriek that could be heard across worlds, Ilservian Palacost was freed. 
After the second time the Hopeslayer is defeated, the Shadows retreat
The first mention hereafter of Ler Rhan is during the Mirror, Mirror event. The island of Caul undergoes a radical change due to experiments of Aerbax in cooperation with Ler Rhan, also referred to as "The Mirror".The island now shows an additional strong Shadow influence. 
During the The War of Blood and Shadow Story Arc, the Shadow Leaders become active again. The three generals, Ler Rhan and Black Ferah on one side, Isin Dule on the other, concentrate their activities on Caul, where Isin Dule keeps a close eye on the whereabouts of the other two 
Ler Rhan's experiments together with Aerbax result in the creation of a Prodigal Shadow Child by the name of Kirienne Palacost.One of his aspects defends the Child, together with an aspect of Black Ferah.
During the Hidden In Shadows patch, a Shadow Spire appeared near the town of Tou-Tou. This was the starting point of a new wave of Shadow activity, led by Ler Rhan and Black Ferah, both now in their true forms, and not as aspects. Though it seems their goal is to bring back Bael'Zharon to the surface, this was merely a test of theories.. In fact, they are collecting information on the ley lines around Tou-Tou in the hope of bringing the Hopeslayer on for a prolonged time, to defeat Isin Dule and to spread the corruption all over Dereth. The Shadows started the attack Tou-Tou and many of the townsfolk decide to evacuate. The siege of Tou-Tou succeeded and the town, and the inhabitants that stayed behind, was corrupted and pulled toward the shadow. The remaining townspeople were turned into shadows, be it weak and unwilling. The event culminated in the reappearance of the Hope-Slayer, and its subsequent defeat by the combined forces of Asheron, Isin Dule, the golem Deewain and even Ulgrim left his favorite drinking spot to give a wack or two with his sword. The forces of Ler Rhan and Black Ferah retreated, though the town of Tou-Tou remains devastated and occupied by the shadow forces and their leaders will keep trying to collect crystals to keep trying to summon the Hopeslayer.