Sid Yggdrasill is a major antagonist in the tokusatsu series Kamen Rider Gaim. As a high-ranking member of the Yggdrasill Corporation, Sid acts as a cunning and manipulative figure, distributing Lockseeds and Drivers to various factions in Zawame City. He transforms into Kamen Rider Sigurd, wielding the Cherry Energy Lockseed. Sid is known for his scheming personality and plays a pivotal role in advancing the corporation's hidden agenda, making him an important adversary to the main protagonists.