Who is protagonist and antagonist in the play?

Antigone, the titular character, is the play's protagonist. She chooses the morally correct route in performing what the gods say she must: she provides a ritual burial of her brother, Polyneices. In doing so, she defies her tyrannical uncle, Creon, who has forbidden the burial and has promised death to anyone who dares to contradict him.
Creon, then, is the play's antagonist. He acts against what the gods have decreed as proper handling of a corpse. Creon is caught up in local politics; he sees Polyneices's act as an attack on his own people, so he takes it upon himself to dishonor his remains. Creon is also angry because his niece dares to publicly embarrass and defy him. Creon's rigidity and defiance of the gods leads to more deaths: Antigone's, Haemon's, and Eurydice's.