What is the name of the Separatist leader and Sith apprentice in Episode II who duels Yoda?

The story behind the answer

He is the public face of the Separatist movement and a Sith apprentice who duels Yoda on Geonosis in Episode II. By contrast, General Grievous is a non-Force-sensitive cyborg commander introduced mainly in Episode III; Darth Sidious (Palpatine) is the hidden Sith Master who duels Yoda in Episode III; and Nute Gunray is a Trade Federation viceroy, not a lightsaber duelist.

A former Jedi Master who took the Sith title Darth Tyranus, he championed secession to destabilize the Republic, secretly recruited Jango Fett as the clone template, and helped engineer the Clone Wars to empower his master. His curved-hilt lightsaber and elegant Makashi form showcase a refined, fencing-inspired style—brought to life by Christopher Lee’s aristocratic presence.