Altered Beasts, commonly abbreviated as A.Beast, are 1 of the 4 attribute classifications given to monsters in Phantasy Star Online. Most altered beasts were mostly native creatures who go through genetic engineering via external sources such as radiation, D-Cell contamination or De Rol Le. As a result, they mutate into horrid creatures.
Most altered beasts attack with unnatural breaths, appendages, claws or scythes made from bone, photon or liquids. Weapons with percent modifiers in A.Beast will do extra damage to any altered beast creatures upon contact, proportional to how high the percentage itself is.
- Mericus, Mericarol and Merikle are the largest non-boss Altered Beasts. Merilia and Meriltas are the smallest.
- Barba Ray is the only Altered Beast that didn't evolve via external sources. As this creature was VR simulated.
- Merissa A/AA are the only Altered Beasts that use known techniques.
- Pan Arms and Grass Assassin are the only two creatures carried over to Episode II. Their stats are altered, but their behavioral patterns aren't.
- The name "Altered Beast" is a reference to another franchise with the same name in Sega's library. It is a beat 'em up arcade game wherein a centurion battles countless monsters. Centurions have an ability to power up by transforming into an Altered Beast after gathering a certain amount of power ups in each stage.