Elesin is the tragic hero in this story. Although the play is based on a true story, Elesin is a tragic hero because he dies to succeed in his mission: committing suicide to join his king.
According to local custom in Nigeria, Elesin must commit suicide after the king dies, so the king will not be alone. He considers this a thing of honor, and throughout the play he tries to kill himself even though the British try to stop him. The others blame Elesin when he allows himself to be arrested instead of killed:
We called you leader and oh how you led us on. What we have no intention of eating should not be held to the nose." (pg. 56)
As you can see, it is very important that the ritual be carried out. In the last act, Elesin says that nothing will ever be the same again, because his ritual was not carried out. Yet when he learns that his son has committed suicide in his place, he manages to kill himself anyway.
Elesin is a hero because he dies commit suicide in the end, even though he is distracted by his bride first.