List of characters that have only been mentioned in 5 Years Later so far.
Notable Characters
Jazz Fenton
Jazz is the sister of Danny and daughter of Maddie and Jack. She was mentioned by Danny in Chapter 1: Alienated when he told his story.
Prior to 5 Years Later she moved to college.
Proctor Servantis
He was a leader of the Rooters in witch base Ben and Rook met Danny in Chapter 1: Alienated.
Prior to 5 Years Later he and the Rooters were taken out by Ben and his team.
Albedo
He was a Galvan and Azmuth's assistant that created a copy of the Omnitrix and was trapped in Ben's body and later on in 11 Year old's Ben body. He is responsible for creating the Ultimatrix (a device that Ben used after the self-destruction of the Original Omnitrix). He was mentioned by Lula in Chapter 5: Oversight.
Not much is known about what happened to Albedo after he was seen last time before 5 Years Later other than the fact that he is still trapped in Ben's body when he was 11.
Dr. Logic
He was a villain that Ben faced when he was 19. After the battle with him, Ben changed his ways of how he used the Omnitrix. He was mentioned by Lula in Chapter 5: Oversight.
The Almighty Tallest
The Tallest are the leaders of the Irken civilization. They have chosen to entire war with the entire universe. Their grand plain of conquering everything is called Operation Impending Doom II.
They have sent Zim to Earth because they don't like him and wanted to get rid of him, but Zim still fully believes that his Tallest loves him. Zim even planning on betraying Eon for the Tallest.