Small, eyeball shaped robots that originate from the Portal series, personality cores are round, white or gray colored, have a large single 'eye' at its center (which may or may not have eye lids), and are usually seen communicating and speaking with those around them.
Their personalities in question are unique to each individual core, but typically focus on a single personality trait to behave as, like Wheatley (klutzy and idiotic), the curiosity core (to be curious and question everything around it), or Rick (to be adventurous and get into trouble for the sake of fun). The cores are only seemingly used to provide support to humans (since they have no weaponry and only seem capable of minor hacking) and to restrict the intelligence of larger and more sophisticated AIs (such as GLaDOS and Wheatley (only during his takeover of the Aperture Science facility though)).
