The lightsaber's amethyst color was chosen by the actor portraying Windu, Samuel L. Jackson, who wanted a purple lightsaber because he was "the second baddest Jedi in the universe" and so he could find himself among the many Jedi featured in the Battle of Geonosis scene.
Jackson wanted his character to wield a purple blade on-screen. Jackson felt that a unique lightsaber color would enable his character to stand out among the sea of sabers on the screen during the chaotic Battle of Geonosis (from Episode II).
Purple combines red and blue. Two primary colours are used to represent the Jedi and the Sith. A Jedi who was turned into the Sith and then returned to the Jedi order is the only one who is thought to possess a purple lightsaber.
Does anyone other than Mace Windu have a purple lightsaber?
In Canon we only have Mace Windu with a purple lightsaber, and Rey Skywalker and the Temple Guards with yellow lightsabers (and Cal Kestis if you choose him to have one in Fallen Order). In Legends Darth Revan and the Dark Woman both had purple sabers, but I think that was it, and Bastila Shan had yellow lightsabers.
In the fictional Star Wars universe, Mace Windu is portrayed as a Jedi Master who sits on the High Council during the final years of the Galactic Republic. He is notable for wielding a unique purple-bladed lightsaber, and is regarded as one of the most powerful Jedi of his time, second only to Yoda.
The black lightsaber, or Darksaber to give it its proper name, is one of the rarest lightsabers in Star Wars canon. Despite its rarity in canon, anyone who has seen the second season of The Mandalorian is likely to be familiar with the Darksaber.
Ahsoka's white lightsabers first appeared in the TV episode "Fire Across the Galaxy", the season one finale for Star Wars Rebels. According to Dave Filoni, one of the show's creators, the lightsaber blades are white to reflect her non-affiliation with the Jedi or Sith.
Din Djarin is the latest character in the Star Wars universe to wield the Darksaber. Collider recalls the season 2 finale of The Mandalorian, where he defeats Moff Gideon and takes the coveted blade for himself.
In the Thrawn Trilogy, Mara Jade started out as an assassin working for Emperor Palpat. Over time, he undergoes a transformation and eventually becomes a Jedi Knight. Her lightsaber is a pink lightsaber, also known as the "Emperor's Hand Lightsaber".
The color of a saber alone does not determine its power; rather, the strength and abilities of a saber are determined by its wielder and the kyber crystal used to power it. Having said that, purple sabers are generally considered the most powerful sabers due to their build and characteristics.
Billaba became Windu's Padawan and trained under the Jedi Master in the ways of the Force. During her training, Windu allowed her to study Form VII variant known as Vaapad. She eventually became a Jedi Knight, renowned for her skills with a lightsaber and favored Form III when teaching other Jedi.
The term “gray Jedi” in Star Wars is somewhat of a misnomer, considering that the definition refers to one who is practically non-Jedi. That being said, quite a few Jedi can be placed into this category. But Mace Windu identified as a Jedi despite his possible inclusion in the "gray" category.
Traditionally, yellow lightsabers are associated with Jedi Sentinels, who balance their combat skills with a strong focus on exploration and practical application of the Force. This choice reflects Rey's well-rounded training and her determination to maintain balance in the Force.
Gray lightsabers are often associated with Jedi who do not fully follow the Jedi Code, but also do not fully embrace the Dark Side. These Jedi are often able to balance the light and dark sides of the Force and use their powers to serve the common good and are less likely to be influenced by the Dark Side.
Luke Skywalker owned three different lightsabers over the course of Star Wars canon, making him one of the franchise's most prominent figures. Luke's blue lightsaber, originally owned by his father Anakin Skywalker, was lost when Vader chopped off his hand in The Empire Strikes Back. It was later buried on Tatooine.
Ahsoka presumably dropped both her lightsabers, though only one is shown, near the graves. By leaving her lightsabers there, Ahsoka faked her own death. Later, Darth Vader visited the moon and found one of Ahsoka's lightsabers. Remembering his former Padawan, Vader took Ahsoka's lightsaber back to his ship.
The Darksaber. The only black blade-like Saber ever made, constructed with fine Beskar, by the only Mandalorian to ever become a Jedi in the Order's entire history.
Sith hate who use Sith who use purple lightsabers because they believe they are not true sith, and they do not like jedi's who use purple lightsabers either because they think that jedi are cheating using dark side of the force and its powers but not fully falling completely to the dark side.
After his reincarnation, Darth Sidious aka Palpatine used a blue-bladed lightsaber when he fought Luke onboard his Super Star Destroyer Eclipse. Ultimately, Sith who wielded colors other than red were usually looking to disguise their dark affiliations.
Look, he definitely isn't Mace Windu's son: the age doesn't match, considering the other character's ages (Luke, Leia, Vader, Solo, etc.). However, i think it's possible to see Finn as his grandson, but for that you must consider that Windu had a secret baby close to his time of death.
A year later, in 4 ABY, with his health rapidly declining, Yoda died of old age when Skywalker returned to see him. He became one with the Force, shortly before Luke redeemed his father Anakin, who fulfilled his destiny as the Chosen One by killing Sidious.
Originally Answered: Is Mace Windu alive in the Star Wars universe? Canonically no, he was declared dead by Lucasfilm after Sidious shot him out the window 3,000 stories off the ground.
