Asbolus (English translation: "sooty" or according to Dieter Koch, "carbon dust") was a Centaur and a diviner who read omens in the flight of birds.
When Heracles came to visit the centaur Pholus, Pholus opened a jug of wine for him. The jug belonged to all the Centaurs; Asbolus saw Pholus do this and brought the other Centaurs running. A battle ensued in which Pholus and Chiron, as well as Nessus, died at the hands of Heracles.
Asbolus warnings failed to keep his friends from war.