Elaida do Avriny a'Roihan is an Aes Sedai of the Red Ajah, and the former Amyrlin Seat in the White Tower. Her strength in the power is 13(1), making her among the most powerful Aes Sedai at the time of the series beginning. She was also the only Amyrlin raised from the Red Ajah in the New Era.
She is handsome and severe looking. She has dark eyes and dark hair to her shoulders. She is 5'6" or 168cm in height.
She was born in 950 NE and went to the White Tower in 967 NE. Elaida was the first novice to be raised to Accepted in only three years. She was raised to the shawl after Siuan Sanche and Moiraine Damodred's second year as novices, in 973 NE, and chose the Red Ajah. Since then she only deferred to the Amyrlin Seat or a Sitter, or to the three known Aes Sedai stronger than her in the Power.
After Moiraine and Siuan came to the Tower, Elaida made life miserable for them, pressing them so hard that other sisters often had to intervene. Her excuse for doing this was that she wanted them to pass. She is there when Moiraine is tested for the shawl, and does her best during the testing to try and make Moiraine fail. She is also present when Moiraine and Siuan take the Three Oaths of an Aes Sedai.
Elaida is what once would have been considered very strong in the One Power by Aes Sedai standards. Although the discovery of channelers such as Sharina Melloy and Nynaeve al'Meara, the reemergence of the Forsaken and the finding of some uncommonly powerful channelers among the Aiel Wise Ones and Sea Folk Windfinders has shown the modern day Aes Sedai just how comparatively weak they are, Elaida is still of above average strength. For a while amongst Aes Sedai, Elaida was only surpassed in the Power by three people - Cadsuane Melaidhrin, Kerene Nagashi, and Meilyn Arganya - and matched by Moiraine Damodred, Siuan Sanche, Lelaine Akashi, Romanda Cassin, and only one or two others. Since the events in the books, there are now three Aes Sedai who greatly surpass her in strength. These are Nynaeve, Egwene al'Vere and Elayne Trakand. A few women in training to become Aes Sedai - namely Sharina, Nicola Treehill , Bodewhin Cauthon and one or two other girls from the Two Rivers - also surpass her in strength, although by that time Elaida has been taken.
Besides her raw strength, Elaida is also notable in having the Talent of Foretelling. She was as strong as any with the Talent at the time, making her a very valuable channeler. Elaida supported the Vileness after the Aiel War, where the Black Ajah manipulated Reds and some others into gentling or killing men suspected of being able to channel. She would not kill anyone herself, but was willing to turn a blind eye. She was one of those who gentled Thom Merrilin's nephew. When the Vileness was stopped by Marith Jaen, Elaida escaped punishment because of her relative lack of involvement; and because it was decided to punish only a few to help keep the Vileness a secret.
Before the Schism
Elaida was in Andor when Rand al'Thor was taken to see Queen Morgase. Elaida had a Foretelling about Rand being in the center of all the pain and division to come to the land. Before she could imprison and question Rand any more, Morgase let him walk from the Throne Room a free man. Elaida later tried to track him down, but Moiraine arrived in town and fled with Rand before she could find him.
When Morgase comes back to the White Tower and finds Elayne missing, she becomes furious and refuses to take back Elaida as her advisor again. Elaida later visits Egwene and Nynaeve while they are in the White Tower, to try and find out more information on Rand. She is one of the Aes Sedai present at Egwene's testing to become Accepted.
A member of the Red Ajah, and a former Sitter for the Red (a position she was unwittingly able to attain with the help of the Black Ajah via Highest Red and Supreme Council-member of the Black, Galina Casban), Elaida served as advisor to Morgase prior to being raised as Amyrlin. After meeting Rand in Andor she leaves Andor frequently, visiting Elayne in the White Tower. This leads to her spotting some unusual visitors meeting and leaving the Amyrlin, in particular Nynaeve and Egwene. She becomes concerned when the two girls with Elayne go missing and lays this at the Amyrlin's feet. Soon the thirteen sisters who are Black Ajah flee the Tower, which again is Siuan's fault. When Min Farshaw acting as Elmindreda is also spotted by Elaida visiting the Amyrlin her suspicions really begin to rise and she begins to plot with Alviarin. When the news of the Dragon Reborn from Tear arrives she gathers a number of Sitters as her close circle and makes her move to take down Siuan as Amyrlin, believing that she has been behind the Dragon's movements this whole time (which isn't too far wrong).
She took over from the stilled Siuan after arranging that Amyrlin's overthrow and subsequent imprisonment and stilling. Elaida is noted for her iron fist, and for seeing the Blue Ajah removed from representation in the Hall of the Tower (though all of that Ajah had fled the Tower after the rebellion in which she took over). Indeed, Elaida has shown unprecedented cruelty and extreme miscarriage of justice where Siuan is concerned. While Siuan is unconscious, she is tried, found guilty of all charges, and stilled, and she probably would have faced execution had she not escaped her imprisonment. Breaking a long held tradition, Elaida elected Alviarin as her Keeper of the Chronicles. Traditionally, the Keeper is of the same Ajah from which the Amyrlin was raised, but Alviarin was of the White Ajah, and also the highest ranking of the Black Ajah. Friction begins to develop between the two, and secretly each plots the downfall of the other. Elaida ordered Galina to capture the Dragon Reborn and bring him to the White Tower, to be held until the Last Battle. Alviarin blackmailed Elaida with the debacle at Dumai's Wells, making her Alviarin's puppet. Then, through a desperate plan, Elaida goes to Seaine Herimon to make inquires and find who helped Siuan to escape (most likely already believing it to be Alviarin), who changed Elaida's orders, and to find and report who entered into a treasonous correspondence with the Dragon Reborn. Elaida tells Seaine to follow the stench of treason (no matter how high - even to the Keeper) and report only to her. Seaine interprets her orders as an order to find Darkfriends among the sisters and enlists the help of her old friend Pevara Tazanovni to hunt out the Black Ajah within the Tower, which might inadvertently lead to Alviarin who, in fact, is a Darkfriend, and corresponded with Rand and controlled the Tower by altering the Amyrlin's edicts without Elaida's knowledge. Elaida has since replaced Alviarin with a Red sister, Tarna Feir, for her Keeper.
Rivalry with Salidar
Elaida believes that she is in a position well above anyone else and has drawn out plans to make a palace for the Amyrlin which will rival the White Tower. Construction for this massive undertaking is well under way. Recently, Beonin Sedai, a spy sent to Salidar under Elaida's direction, returned, told Elaida of their plans, and showed her Skimming, how to Travel, and several new forms of Healing. She also plans to break Egwene al'Vere, the Amyrlin Seat of the Salidar Aes Sedai, who was recently captured while attempting to turn the giant chains to the tower gates at the harbor into cuendillar. She has reduced Egwene to the status of a novice, an action rarely taken by the Amyrlin unless called for by desperate measures. Acting on orders from Yukiri, Meidani attempts to renew the relationship she shared with Elaida when they were novices. However, Elaida is well aware that Meidani is a spy sent by the rebel Aes Sedai.
Seanchan attack on the White Tower
She has Egwene serve her dinner with Meidani, in an attempt to see how Egwene reacts. Mistaking Egwene's stony silence as being broken, Elaida thus continues her discussion with Meidani about the lack of obedience the Aes Sedai show towards the Amyrlin Seat, going so far as to contemplate a fourth oath of obedience to the Amrylin. When Egwene spills the soup on purpose in retaliation, Elaida threatens to send her to the dungeons and sends her to Silviana for another strapping.
As the book progresses, Elaida passes down an order for Egwene to do only chores in an attempt to humiliate her further and break her into subservience. That same day, she summons Egwene to wait on her again, this time with a company of Sitters. When Elaida unwittingly forces a confrontation with Egwene regarding her dream, Egwene clashes with Elaida in front of the Sitters verbally, bringing up Elaida's tyrannical attitude towards the sisters and the idiocy of her plan to kidnap the Dragon Reborn. When Egwene finally loses her cool and insults Elaida, Elaida loses her rationality and starts beating Egwene with switches of Air, and throws her into the dungeons.
When Silviana finally has had enough of Elaida's treatment of Egwene and denounces Elaida in front of the entire Hall, Elaida puts Silviana in Egwene's place and raises Katerine Alruddin as Mistress of Novices. After being chastised by the Hall, she remains as the Amyrlin, but her position is now tenuous with regard to the Hall. Later that same night, when the Seanchan raid the White Tower, Elaida is taken and renamed Suffa. She is later brought before Fortuona, Empress of Seanchan, and forced to demonstrate Traveling.
Fortelling about the importance of a Royal line of Andor in the Last Battle
This foretelling is obviously linked to Rand via his mother Tigraine Mantear. Elaida misinterpreted this foretelling as she did not have all the facts about the correct Andoran line of succession and instead attached herself to Morgase of House Trakand.
Fortelling about Rand in Caemlyn
To everyone's ears: "This I Foretell, and swear under the Light that I can say no clearer. From this day Andor marches toward pain and division. The Shadow has yet to darken to its blackest, and I cannot see if the Light will come after. Where the world has wept one tear, it will weep thousands. This I Foretell." 
To only Rand's ears: "This, too, I Foretell. Pain and division come to the whole world, and this man stands at the heart of it. I obey the Queen, and speak it clearly."  "And Elaida had seen chaos swirling around him, division and strife for Andor, perhaps for even more of the world."  This is linked to Rand being the Dragon Reborn and casting all nations into chaos. Andor underwent its far share of pain and chaos with Rahvin putting Compulsion onto Morgase. Rand then defeats Rahvin but this then creates a war of succession, with House Trakand against House Traemane.
She had a Black Tower Foretelling and interpreted it to fit her own designs.