Watagash

Watagash is a dangerous parasitic alien criminal who escaped Galactic Patrol custody during Dragon Ball Super. He amplifies the negative emotions of his hosts, transforming them into monstrous fighters, with his power scaling directly to how much evil resides in whoever he possesses.

Gohan fought Barry Kahn after Barry was possessed by Watagash. The arrogant movie actor's intense jealousy toward Gohan made him an ideal host, and the Barry-Watagash fusion became a towering creature powerful enough to overwhelm base Gohan before Super Saiyan Gohan defeated the monster with a Super Kamehameha, deliberately holding back to avoid killing Barry.

Watagash was a tiny, cotton ball-like parasite captured by the Galactic Patrolman Jaco. While Jaco stopped for ramen, Watagash escaped and fled to Earth, where he began searching for hosts driven by negative emotions.

Watagash's first host was a bank robber, who gained enough power to challenge Gohan in his Great Saiyaman persona before being defeated with a single kick. Watagash then latched onto Barry Kahn as his next host.

His name is a play on "watagashi," the Japanese word for cotton candy. This naming references his small, cotton ball-like physical appearance in his unattached form.