Laughing Bull (ブル?) was a nomadic Native American living on Mars with his son. He practiced Native American customs and gave advice, which often sounded cryptic to outsiders. He knew Spike Spiegel and Jet Black and would help them occasionally.
Spike seeks out Laughing Bull in order to track down Asimov Solensan, a drug dealer with a bounty on his head. Laughing Bull correctly predicts that "the red-eyed coyote" will appear in Zona Norte, in the far side of town. Using this information, Spike confronts Solensan and attempts to apprehend him. 
After Gren conducted a Red Eye deal with Vicious, Laughing Bull observed a shooting star with his son. He saw it as the "tear of a warrior" and "lost soul who has finished his battles." Also, he could not find his way to the "great spirit." 
After the first fight with Vincent Volaju on the train car, Spike fell into the river and slipped into unconsciousness. He woke up to see Laughing Bull and another who had apparently saved him by hauling him out of the water and treating his wound. Here, Bull referred to Spike's two different eyes, calling one of them the "eye of truth," and stating that Spike has nothing to fear of death. He also referred to Spike by the name "Swimming Bird." 
After Spike left the Bebop to confront his past with Vicious, Jet sought out Laughing Bull to find out where Spike is (though he believes it is a ridiculous idea). Laughing Bull explains to Jet (whom he calls Running Rock) that all living creatures that breathe have a guardian star and that this star falls when the creature dies. He foretells that Spike's star is about to fade and also tells Jet that he should not fear death.
- "Do not fear death. Death is always at our side. When we show fear, it jumps at us faster than light, but if we do not show fear, it casts its eye upon us gently and then guides us into infinity."
He is visually inspired by Sitting Bull, A real-life native holy man.
It is not certain to whom Bull's comments about the shooting star apply, but many have speculated that Laughing Bull is talking about Gren or Lin. The shooting star may have in fact been Gren's spacecraft falling and burning in the atmosphere while en route to Titan. 
Laughing Bull's prediction coincides with the fading of the bright blue star during the credits of the session and its theme song, Blue. 
The reference of Bull to Spike as Swimming bird may be a reference to some older, closer bond between the two of them.