Aristotle's Definition of Tragedy

  imitation button action serious complete magnitude language embellished parts of the ply persons performing pity ad fear purification tragic acts  

Philoctetes

δρώντων / persons performing

Here again, Aristotle distinguishes tragedy from epic poetry, which is not performed, but narrated.

Note that Aristotle talks of performers (elsewhere called δραματικάς, δραματοποιήσας) not characters. Character is a moral or ethical quality assigned to the doer of an action as a result of that action. This is discussed in the section of the Poetics devoted to character.