Oroonoko's courage, battle skills, and strong moral code resemble those of a hero in epic literary traditions. His education, wit, and love for his wife Imoinda resemble the traits of a medieval literary hero. He's an African general beloved by his people, retaining his dignity in slavery. White settlers are impressed by Oroonoko's Western education, innate intelligence, and diplomacy. Oroonoko becomes a tragic hero toward the book's end when he is executed after leading a failed rebellion.
Imoinda is well mannered, gentle, and modest. She is exceptionally physically attractive, inspiring desire in every man she meets, including both Oroonoko and the king. She is also respected by the settlers and slaves in Suriname. In Suriname she reveals herself to be a courageous fighter who has an honor code almost as strong as Oroonoko's. In many ways her positive qualities mirror those of Oroonoko's.
Based on Behn, the narrator views the colony of Suriname through the lens of a British explorer. She's fascinated by the nature and the customs of the native people. Though she befriends Oroonoko, she fears the larger population of slaves, worrying about the possibility of mutiny. She objects to Oroonoko's harsh treatment at the colonists' hands. Still, she's invested in England's prosperity and may or may not oppose the practice of slavery for financial gain.
Byam is well spoken and appears friendly to Oroonoko. In reality, however, Byam is vicious and controlling. He is the main advocate for brutal punishment of the slave rebellion's leaders. He fails to keep his word to Oroonoko after the slaves' surrender. Byam represents the worst instincts of powerful slave traders in British colonies.
The king rules by divine right and abuses his power to secure Imoinda as one of his wives. He is controlling and adheres strongly to tradition. Though he regrets his decision to sell Imoinda to slavery, a fate considered worse than death, he lies to cover up what he's done. The king's tortured conscience contrasts with Oroonoko's strong honor code, which doesn't allow treachery.
Trefry is witty, intelligent, and fascinated by Oroonoko. He is portrayed as more compassionate than most slave masters, such as when he stops his advances on Imoinda in the face of her modesty and nobility. Oroonoko trusts that Trefry will act in Oroonoko's best interest. However, this trust proves misguided when Trefry is powerless to stop Oroonoko's beating and execution.