Penny

Penny is the primary female character on the show, befriending her across-the-hall neighbors Leonard Hofstadter  and Sheldon Cooper , two physicists who work at the nearby Caltech University. Penny's lack of advanced education but outgoing personality drastically contrast the personalities of the primary male characters in the series, even though she is considered part of their group. She also is the love interest of Leonard . In contrast to the rest of the group, Penny is not well-educated (though she is smart) or savvy in a specific technical field, but she has great social skills and is very knowledgeable about pop culture. She is also messy and disorganized, but appears to like it that way.
Penny is portrayed by Kaley Cuoco