Proton bombs were powerful explosive weapons carried by bomber craft such as BTL-A4 Y-wing starfighters and TIE/sa bombers. The bombs themselves were spherical in appearance, although when stored in cylindrical containers, they could also be used as high-yield explosives capable of producing great damage to heavily armored vehicles such as AT-ATs.
A proton bomb being deployed by a TIE bomber
During the Clone Wars, the Confederacy of Independent Systems' Navy used Hyena-class Droid Bombers that carried proton bombs during the Battle of Christophsis. The Galactic Republic Navy's BTL-B Y-wing starfighter/bombers also used proton bombs extensively during the War. During the Ryloth Campaign, the Separatist forces once again employed Hyena bombers, this time to carpet-bomb numerous villages on Ryloth in a failed attempt to scapegoat the inevitable Republic victory as a bloodbath.
Proton bombs were used by the Galactic Empire during the war against the Rebellion. These bombs were highly sought after by the rebels.
A Resistance proton bomb painted with "HAN SAYS HI" in Aurebesh
Decades later, during their war with the First Order, the Resistance carried proton bombs into combat by MG-100 StarFortress SF-17 bombers. Proton bombs in Resistance StarFortresses were often decorated with cartoons or defiant messages towards their enemies. They were used to bomb the Fulminatrix, a Mandator IV-class Siege Dreadnought during the evacuation of D'Qar. While the bombers suffered heavy losses—especially when three bombers were lost in an explosive chain reaction from a TIE fighter crashing into one of the bombers' bomb bays—a lone bomber crewed by one survivor, Paige Tico, managed to drop its entire payload on the dreadnought, destroying both itself and the dreadnought.