A Badass Guardian is a much larger, more powerful version of a Principal Guardian, also primarily using melee attacks to do damage. These are distinguished from the other guardians by their larger size, a slightly different glow to their armor and a larger protrusion on their backs.
Shock weapons are a valuable asset against Badass Guardians, as their durability is mainly supplied by their shields, which are easily depleted by shock weapon attacks. They have a moderate base health, higher than other Guardians, yet still comparatively lower than most enemies.
Equipping a shock artifact is a very effective tactic for empowering any action skills being used against a Badass Guardian. Hunter also make good use of his Trespass skill to ignore the shield of any guardian.