There's Salvor Hardin. He plays a major role in the early days of the Foundation, using political acumen to protect it. Also, Gaal Dornick, who starts as a young mathematician brought to Trantor by Hari Seldon. He becomes involved in the events that set the Foundation's path. There are many other characters as well, each contributing to the complex tapestry of the story's plot.
The complex world - building. It creates a vast galactic empire with diverse cultures and technologies.
Hari Seldon is really important. He's the one who developed psychohistory.
Hari Seldon is really memorable. He's the one who developed psychohistory. His foresight and planning set the whole story in motion. Then there's Salvor Hardin. He was very clever in dealing with the political situations on Terminus. Another is Gaal Dornick. He was important in the early parts, as he was brought to meet Hari Seldon and became part of the Foundation's story from the start.
There are also antagonists like the Inquisitors. They are terrifying and powerful beings that serve the Lord Ruler. Their appearance, with spikes through their eyes and other body parts, and their abilities make them formidable foes for the main characters. Each of these characters, whether protagonist or antagonist, adds depth and complexity to the overall story of the Mistborn series.
The two main characters are Jack Aubrey and Stephen Maturin. Aubrey is a naval officer, brave and skilled in naval warfare.
In the 'Sherlock Holmes' books, the main characters are Sherlock Holmes and Dr. Watson. Holmes is the brilliant detective and Watson is his assistant and chronicler. In the 'Hercule Poirot' series, it's Poirot, the Belgian detective with his unique moustache. And in 'Nancy Drew' series, Nancy Drew is the main character, a young and resourceful detective.
Karrin Murphy is an important character too. She's a police detective who often teams up with Harry. Their relationship is an interesting mix of professional respect and personal friendship, and she helps ground the series in the more 'normal' world while also being involved in the magical happenings.
FitzChivalry Farseer is one of the main characters. He's a complex character with a lot of growth throughout the trilogy.
The main character is Kvothe. He's a very complex character with a lot of depth. His story of growing up, facing hardships, and his pursuit of knowledge and power is central to the series.
One of the main characters is Logen Ninefingers. He is a complex character with a violent past.