I originally thought Erik Killmonger was going to be a rather dumb villain in the Marvel Cineamtic Universe, but he turned out to be one of the best. You at first think he's just some guy looking to exploit the key metal that makes Wakanda so powerful. And stops at almost nothing to achieve his real goals.
Which is to be the new King of Wakanda. While it seems like he's just American, his is the son of T'Challa's exiled uncle. Which gives him a considerable claim to the throne.
Which is decided through a noble fight without suits or special technology. He manages to best his cousin and throw him down the waterfall.
With everyone believing T'Challa was dead, Erik becomes the new king. Like his father, Erik became a radical after seeing the horrors of what happened to people of color all over the world. He decides to become like the men he hates and wants to use Wakanda's army and technology to not just be ahead of the world, but to rule it.
When Black Panther returns, half of the Wakanda army goes into a civil war of a battle. But this time, Erik has a Black Panther suit.
Luckily T'Challa had his old one. And they fight a match that's a pretty even stalemate.
That's until T'Challa uses a trick in technology to open up vulnerability which mortally wounds him at the right moment. I was glad to see his demise, but I thought it was nice to let T'Challa make peace with his first cousin before he passed away for good.