In Wonder Woman, Diana teams up with Steve Trevor and his men, one of which is known simply as The Chief. The Chief, played by Eugene Brave Rock, is a Native American smuggler that plays a big part in helping Diana and Steve save the world. While watching the movie, the audience only ever knows him by his nickname, unless they can understand Blackfoot.
Diana is shown to speak many languages, one of which is the Native American language of Blackfoot. Every time she speaks a language besides English, her words are accompanied by subtitles for the benefit of the audience. The only time her words are not translated is when she and Chief are introduced. Chief introduces himself in Blackfoot, subtly revealing that his name is Napi. Napi is the name of a Blackfoot demigod.
According to Indian Country Today, Napi is a Blackfoot trickster and storyteller. Native Languages’ page on Napi says he is also known as Old Man and is a Blackfoot culture hero. He is a trickster that is also a well-intentioned demigod that frequently taught people important knowledge. He and his wife Kipitaki, also known as Old Woman, were the first man and woman made by the Creator and made the rest of humanity. The page has links to some stories about Napi, such as one that explains why humans rule over animals.
To respect his heritage, Wonder Woman director Patty Jenkins gave Brave Rock a lot of creative control over different aspects of his character, such as Napi’s wardrobe. However, the introduction between Napi and Diana was not improvised. The name Napi was part of the script. On Twitter, Brave Rock confirmed that Chief is not just named for the demigod, but he is actually the demigod himself.
This doesn’t necessarily mean that we will see Napi again in any DC films, but it does leave that possibility. A Wonder Woman sequel set in present day could include Napi, since aging would not be a problem for a demigod. It would be pretty interesting to explore Diana’s friendship will a fellow immortal, so hopefully we’ll see him again.