Star Wars: Why Was Count Dooku Called Darth Tyranus?
"Star Wars" is filled with memorable villains, from the insurmountable Darth Vader to Emperor Palpatine and Darth Maul. Not every fan-favorite bad guy has a red lightsaber on their hip, but it certainly helps to make you memorable. But out of all of the core Sith in the franchise, one has always been kept out of the center spotlight: Count Dooku.
Even though he was played in the films by the one and only Christopher Lee, he's never truly taken center stage. Make no mistake, Count Dooku is a great villain. He has plenty of fans within the more dedicated "Star Wars" fandom. He's also gotten some great development in more extraneous stories since Disney took over the franchise, such as the audiobook "Dooku: Jedi Lost" and the animated series "Tales of the Jedi." But in the grand scheme of things, he just isn't all that important. Darth Maul gets to come back after being "killed" by Obi-Wan Kenobi and becomes a huge villain in his own right, but Dooku is mostly treated like a puppet with a funky lightsaber.
Perhaps his problem is simply with branding. See, all the other Sith get cool names, but Dooku is just the Count of Serenno. Of course, he does have a proper Sith name — Darth Tyranus — but he rarely goes by it. But how did he get the name? And why doesn't he ever use it?
Dooku had a complicated path to becoming a Sith
Every Sith worth their salt gets a "Darth" name — Sidious, Maul, Vader, the list goes on and on. And when he formally becomes Palpatine's apprentice in the wake of "The Phantom Menace," Count Dooku receives his own Darth title: Tyranus. Of course, Dooku had already left the Jedi Order years before, and he'd been working as an agent of the Sith Lord for some time. But it was only after Maul was seemingly killed that Dooku fully gave himself over to the dark side and bled his kyber crystal red.
Given that Palpatine gives Anakin the title of Darth Vader, it's safe to assume that he also chooses Dooku's Sith moniker. There's no official significance behind the "Tyranus" name other than that of most Darth titles. Like Sidious and Vader, it suggests a level of evil and aggression, evoking words like tyrant and tyranny. But it may be telling that Dooku never really came around to using the name.
Even after officially becoming one, Dooku doesn't really display the traits that we associate with other Sith. He's evil, yes, and he kills many people, but he doesn't possess the same unceasing thirst for power that drives Sidious and Maul. And because of his unique role in Palpatine's master plan, many people likely never even thought of him as a Sith Lord.
Why didn't Count Dooku go by Darth Tyranus publicly?
As the leader of the Separatists, Dooku goes by his proper name, not his Sith title. This is a strategic decision. Because he's the Count of Serenno, a major Outer Rim world with lots of political influence, he's uniquely positioned to organize the secessionists and command authority among them. That's the original reason why Palpatine recruits him, and he uses Dooku's disillusionment with the corrupted Republic and Jedi to win him over.
There would be no real gain in Dooku using his Sith title publicly. The old order means little to most people in the galaxy during the Clone Wars, and claiming to be a Sith might even turn more public sentiment against him. The only times we hear the Tyranus name mentioned in the movies are in reference to the Kamino plot. Dooku hires Jango Fett under the Tyranus name, which obfuscates the true nature of the scheme during Obi-Wan's "Attack of the Clones" investigation. In this way, Dooku uses his Sith title more like a code name or a secret identity than a bold declaration of his Sith powers.