|I...would choose to have never been born, if it was up to me. I've hated my blood. More than anyone else...I wished for the extinction of all Eldians. ...but I do not wish to die. Because...I was born into this world.|
|— Willy opens up to the world|
Willy Tybur was a man of average stature and had the appearance of a well-groomed man, wearing an expensive, dark suit with a black tie, and smart black shoes. His hair was blond and straight, going down to shoulder length and styled over his right ear, but behind his left where it is shorter. He had a short beard styled as a goatee, with no mustache. His face was of an average length, with soft features, except a pronounced jawline, a relatively small nose, and dark eyes. Willy had thin eyebrows, appearing to be kept this way to fit in with his well-kept appearance. He appeared to exude lots of confidence and charisma as he stood.
As befitted a man of his status, Willy conducted himself in a very dignified manner, treating others with courtesy, as evidenced by his interactions with Magath. However, he also showed the propensity to joke around with others, as seen by his joking invitation for Magath to try to identify the holder of the War Hammer Titan among his family members. Willy also seemed to be a naturally cautious person, going to great lengths to make sure that he and his family are kept out of the public's eye at all times, even going so far as to have the owner of the Warriors' headquarters removed prior to his visit.
Willy appeared to be a somewhat honorable man, electing to allow the Marley government to act as it pleased without his input, including the subjugating of Eldian citizens, as a form of penance for his ancestors' brutal treatment of the Marleyan people during Eldia's reign. He was also extremely charismatic and was able to sway those in attendance to support his efforts to eradicate the remaining Eldians on Paradis, despite revealing the history of Marley that was presumed to be common knowledge was a mere fabrication by both his family and the king, Karl Fritz.
As a child among nobility, Willy Tybur made friends with other children in foreign nations, such as Nambia. Some time later in his life, his younger sister inherited the power of the War Hammer Titan.
When Willy Tybur became the head of the Tybur family, his sister revealed to him the truths of the Tyburs and their dealings with Karl Fritz during the Great Titan War. Shocked and appalled by the true nature of his bloodline, Willy Tybur felt the burdens of his position and the weight of his forebears' sins, and he was filled with a new determination to right the wrongs committed against the Eldians and save the nation of Marley from its inevitable decline.
Due to concerns that the Eldian race has been put at risk with the world's growing technological advantage over the Titans, the Tybur family agrees to cooperate with Zeke Yeager and the Warriors and take action in the next mission against Paradis using the power of the Tybur family's War Hammer Titan.
Speaking with Magath privately, Willy claims that they came to see the statue of Marley's legendary warrior named Helos, and is taken aback by Magath's snide comment that the hollow statue reflects Marley's spirit. Willy asks if it is true that Magath plans to revive the Marley conscription system, and Magath informs Willy that it is too late to change anything, as Marley's warlike nature is slowly leading the country to its destruction. Noting Magath's insinuation, Willy reveals that the Tyburs are the true rulers of Marley, and that they have been allowing the Marleyan government to act as it pleases as a form of penance for the country's suffering while under Eldian rule. Feeling guilty for his family's inaction, Willy tells Magath that he will reveal the family's secrets to the world at the upcoming festival, and entreats Magath to work with him.
A month later, Willy meets up with Magath and congratulates him for his previous promotion to the rank of general after the latter hands him a small note. They have a conversation about the military and their country, during which Willy expresses his discomfort from the pressures of being forced to lead the nation.
That evening, he is present for the welcome party for ambassadors who have come to Liberio, politely saluting them and cheerfully greeting his childhood friends. After a Marleyan ambassador delivers an underwhelming welcoming speech, Willy takes his place, talking about Marley's history and the issues Titans have caused to the world. Claiming to understand the hatred the world feels for his fellow Eldians, Willy announces that he has devised a solution to the problem Eldians pose for the world, and promises to explain it to everyone during the festival the following day.
As Willy and Magath head to the festival, they discuss the security involved in order to protect Willy and the officials present. Magath does not think it will be possible to defend everyone, but Willy wants to be on stage during the event and to bait their enemies with as many military officers as possible. Willy tells Magath he can limit the officers to the useless ones, leaving him free to rebuild the military with whoever he likes. When Magath is still hesitant due to the number of Eldian civilians present, Willy points out that Magath has sent crowds of them into machine fire before without any issues and expresses curiousity as to why Magath now is exhibiting reluctance to do it once more; he tells Magath to simply continue doing what he always has.
When Magath admits he is concerned for Willy's safety, Willy explains that the world will not pay attention unless he stands on the stage before it. It is important that the Eldians in the internment zone become tragic victims, himself included. The world would not take his side if he was the only one to escape.
Backstage, before the play begins, Willy is informed that it is time to go speak to everyone. He is greeted by Kiyomi Azumabito, who comments that he must look terrible, but she says that he is brave and hopes he fulfills his duty without incident. Willy then comes on the stage and tells the story about the bloody history of Marley and Eldia. The Eldians ruled the world by utilizing the power of the Titans. According to their information, the number of people lost from then until now is estimated to be three times that of the current global population, including the eradication of numerous ethnicities and cultures. The Great Titan War began once the enemies of Eldia were all gone, using eight of the Titan powers to constantly fight amongst each other. Then the Marleyan hero Helos aligned with the Tybur family to force Karl Fritz to flee the island, but he left with the powers of the Founding Titan in his possession.
Willy goes on to discuss the failed Paradis Island Operation with the return of only one out of the four Titans that were originally sent, as well as the thirty-two survey ships sent in the last four years which none have returned, affirming the Eldian Empire's survival. He declares the truth for the first time: it was not Helos nor the Tyburs who were the heroes of Marley, but King Fritz. A pacifist, he took pity on Marley and aligned with the Tybur family, fabricating the deeds of the hero Helos.
Willy reveals that Fritz and the Tyburs were behind the collapse of the Eldian Empire and mentions that the King's threat of unleashing the Wall Titans if their peace was disturbed was also a lie. His belief of peace would be carried down with his successors, as well as freedom for Marley. The Founding Titans would be held to Karl Fritz's vow of renouncing war, and if the day should come when Marley arrives to destroy Eldia, they would accept it. However, Karl Fritz's final wish was for a brief paradise; a world without conflict. As the crowd begins to wonder about this revelation, Willy proclaims that the desire for peace was destroyed by the recent rebellion that has taken place on Paradis. Proclaiming that someone of non-royal blood has taken the powers of the Founding Titan, he states the world is now facing yet another crisis. A rebel against peace is coming for Marley, and his name is Eren Yeager.
Willy explains that the three Walls are comprised of millions of Colossus Titans to serve as both shield and spear for Paradis. The vow Fritz took prevents the royal bloodline from using them against the world, but Eren can activate that power despite his unclear connection to the Fritz family. If Eren manages to command the Colossus Titans, not even all the world's advancements in military technology will be enough to stop them.
Given the choice, Willy claims that he would never have been born, but now that he has, he wishes to live. He asks the crowd if they would be willing to lend him their strength to ensure a better future together. The crowd rises in a frenzy and Willy declares war as the Attack Titan bursts out from the building behind him. Willy can only look up in horror as the Attack Titan raises its hand and smashes it down on to the stage, crushing him. Then it flings Willy's body into the air, splitting it in two.
After devouring Willy's body, Eren next attacks the assembled military officials in the audience. While he does so, Willy's sister frees herself from the rubble of the broken stage. Thanking her brother for performing an outstanding duty for the Tybur family, she then transforms into the War Hammer Titan.
- Theo Magath - Although they only knew each other for a month, the two developed a strong respect and comradeship. Willy trusted Magath, revealing the true role of his family the first time they met, and sought his cooperation in rebuilding Marley. When Willy was prepared to sacrifice himself in order to rally the world's nations, Magath seemed distressed at the proposal, saying he was too important to act as bait. Despite this, they agreed to this plan for the sake of their country.
- Willy comes from the Germanic name "Willahelm," with "Will" meaning desire and will and "helm" meaning helmet. The name "Tybur" appears to be a variant spelling of the name "Tiber," which is itself a variant of the Latin name "Tiberius." "Tiber" is also the English name of the river which runs through Rome and the third largest in Italy.