The Blue Leader is an antagonist in Ben 10: Alien Force. He led the blue army during a civil war on his planet.
The Blue Leader is a short, teal-skinned humanoid, wearing a blue military suit. He has a large nose, white mustache, no visible eyes and a monocle.
When Ben Tennyson as Spidermonkey goes to question the blue aliens, the Blue Leader uses a gas to put him to sleep. The blue aliens tie Spidermonkey up. A young girl of the blue aliens tries to stop them but they don't listen to her. Before the blue aliens can shoot him down, Gwen Tennyson uses a Mana shield to protect him. Later, the blue aliens have lunch and the Blue Leader says them same as the Red Leader that the red aliens are attacking them.
Later, on a ship, the Blue and Red Leader argued about their species' sage's color. The Red Leader said that he was red whilst the blue leader said that he was blue. After arguing, they started fighting. Ben as Humungusaur stopped the fight. When Ben tried to shake hands with the Blue Leader, Ben found out that the blue aliens shake with their left hand whilst the red aliens shake with their right hand. The war started again.
Later, Ben got the two leaders to sign a peace treaty. Both of the leaders shined a light at Ben's face causing him to fall of a cliff but Ben saved himself as Goop.
When the war started Ben as Waybig tried to stop them and accidentally destroyed the statue of their sage. Later, the armies declared a war against Ben and merged their affiliations together as one, a purple army, causing Ben and his team to escape their planet.