I, Robot is both a collection of short stories (written by Isaac Asimov) and a movie, which features Will Smith.
I assume you are looking for characters from the nine short stories by author Isaac Asimov from 1940 to 1950 (and not from the 2004 movie with Will Smith). The short stories are wonderful, and you are lucky if you get to read them. I recommend you use this answer as a guide as you read through the stories. The robots protect humans from their own flaws, and Asimov prompts readers to think about the benefits and risks of technology.
Susan Calvin is a psychologist for robots. She does not show emotion (she is described as a “frost girl” in the introduction). Her interviews help readers connect the dots between the various stories.
Lawrence Robertson is president of “US Robots and Mechanical Men, Inc.”
Peter Bogert is a villain and math expert.
Dr. Alfred Lanning is the classic mad scientist and the lead researcher at US Robots.
Robbie is a robot who develops a relationship with young Gloria.
Herbie is a robot who can read minds.
QT-1, otherwise known as “Cutie,” is a robot who is a bit arrogant and wants others to worship him
Gregory Powell is a robot tech. He is less emotional, and he follows the rules
Michael Donovan is a robot tech who works with Gregory. He has a hot temper, but when he and Gregory are together, they are quite funny.
Gloria Weston is a typical little kid who loves to play with Robbie, and she is very upset when her parents get rid of him.
Grace Weston is Gloria’s mom. She is also a housewife, and she is very nosy.
George Weston is Gloria’s dad, and he avoids conflict with Grace.
This is a start, but again, you should start with the first short story and read your way through them. Not every character appears in every story.