The first season of The Mandalorian was an epic, classic Star Wars saga that captivated an audience of millions and put the new streaming service Disney+ on the map. The Mandalorian likes to keep most of it's characters shrouded in secrecy, and one of the most mysterious players that was only even revealed in the back end of The Mandalorian's first season is a man named Moff Gideon. He is a former Imperial officer and an apparently brutal and violent leader, but we don't know much more about him than that.
In the final moments of the season finale, a presumed dead Gideon actually cut himself free from his crashed TIE-fighter, and he emerged from the aircraft wielding a unique weapon that thrilled hardcore Star Wars fans and mystified and confused casual viewers. But the weapon that Gideon had in his grasp is something known as the Darksaber, a legendary weapon that has a long and colored history with the Jedi, Sith, and the Mandalorians. And this is every known person who has been in possession of the Darksaber so far.
Tarre Vizsla
Tarre Vizsla is one of the most unique legendary characters in the entire Star Wars universe, and it can't be a coincidence that the Darksaber (that originated with him) has been introduced into The Mandalorian.
Tarre was actually the very first Mandalorian to be inducted into the Jedi Order, and when he built his lightsaber he came up with this incredibly unique "Darksaber" instead. Understandably, Tarre's success with the Jedi Order made him a bit of a living legend among the Mandalorians, and his skills as a leader as well as his skills in battle wound up elevating him to the level of Mand'alor (the ultimate leader of the Mandalorian people). And after Vizsla's death the Darksaber was stored in the Jedi Temple for quite a while, until other members of House Vizsla broke in and took it for themselves.
Pre Vizsla
It's unclear when the Darksaber was taken from the Jedi Temple and returned to the hands of the Vizsla family, but it's safe to say that it was safeguarded and kept in secret by the Vizslas for up to a thousand years.
It's actually unknown who exactly was the keeper of the Darksaber for centuries after Tarre died, and that remained a secret until one of the descendants of Tarre Vizsla, a Mandalorian by the name of Pre Vizsla, began using it out in the open. Tarre lived in the era before the Galactic Republic and Pre lived towards the end of it's reign, which leaves at least a thousand year gap between them. Pre was the leader of a radical Mandalorian group called Death Watch, and after a few failed attempts he and his group ultimately took over the planet Mandalore themselves.
Darth Maul
Pre Vizsla was undoubtedly one of the strongest fighters in the entire galaxy, but he unfortunately found out that Darth Maul was more than his match a little too late. Although Vizsla initially helped Darth Maul and hoped to form an alliance with him, Maul realized that Vizsla's position of power was something he could use to his own advantage.
In hopes of overtaking the Death Watch for himself, Maul challenged Pre to a duel, a duel which Maul wound up winning. And as a result of killing Pre, Darth Maul claimed the Darksaber as his own. Maul's hold on the Darksaber seemed to be a bit tenuous, as it fell out of his possession a few times in the interim, but it was his until another Force sensitive intervened and took it from him.
Sabine Wren
Maul managed to hold on to the Darksaber for quite a while, but while he was holed up in a hideout on a planet called Dathomir a Jedi named Kanan Jarrus and Mandalorian named Sabine Wren raided said hideout. It would seem that fate intervened to get the Darksaber back into more capable hands, because Sabine took the saber for herself.
After some initial hesitance to wield it, Jarrus convinced Sabine that the Darksaber could be a powerful weapon for her and a powerful tool for leading the Mandalorians as well. And as an experienced lightsaber user, Jarrus began training Sabine on how to wield the weapon for herself. Later, the saber was briefly taken from her by another Mandalorian, but she bested that Mandalorian in combat and the Mandalorians collectively declared that she was the blade's rightful owner.
Kanan Jarrus
Sabine Wren had some understanding of what exactly she had stumbled upon when she found the Darksaber, but she initially didn't want anything to do with it. In order to avoid the enormous Mandalorian responsibility that went along with the Darksaber, Sabine handed the saber over to her friend Kanan Jarrus, who recognized it as a very unusual lightsaber but knew very little more about it than that.
Jarrus held on to it for safekeeping, but after investigating what exactly the Darksaber meant Jarrus realized how important it was to the Mandalorians, and he encouraged Sabine to take it back. Jarrus then began training Wren in how to use the saber for herself.
Bo-Katan Kryze
Initially it seemed as if Sabine may have been the one who was destined to wield the Darksaber, but Sabine grew to believe that she wasn't it's intended target, and that she in fact had been brought to the Darksaber because she was destined to deliver it to it's rightful owner. And she also believed that it's rightful owner was Bo-Katan Kryze.
Bo-Katan was a member of a very prominent Mandalorian family and was one of the key players in the organization Death Watch, but once Darth Maul tried to take over Death Watch and the Mandalorians Kryze stood up against him. Sabine Wren had been seeking a Mandalorian that was worthy of keeping the Darksaber and becoming Mand'alor, and she believed that Bo-Katan was that person. She handed the blade over to her, and Kryze did become Mand'alor.
Moff Gideon
So this is where the history of the Darksaber once again gets a little fuzzy, but it seems safe to assume that The Mandalorian is going to fill in many of those gaps in season 2.
Up until the very last moment of The Mandalorian, it was assumed that the blade was still in the possession of Bo-Katan, or at least in the possession of whoever was now Mand'alor.
However, given that Moff Gideon has murdered many Mandalorians, it seems safe to assume that he killed whomever had the Darksaber previously and has now been wielding the weapon himself. Time will only tell if Din Djarin, or even possibly baby Yoda, will be proven to be the rightful owner of the Darksaber now.