nonconformist
A person who refuses to follow what most people do.
A nonconformist is someone who refuses to go along with what most people do or think, choosing instead to follow their own path.
When everyone in your class starts wearing the same style of sneakers because they're popular, a nonconformist might wear completely different shoes, not to be difficult, but because they genuinely prefer their own choice. When a scientist challenges an accepted theory that everyone believes, she's being a nonconformist by questioning what others take for granted.
Nonconformists often face pressure to change. Other kids might make fun of someone who does things differently, or adults might call them stubborn or rebellious. But history shows that nonconformists often drive important changes. Scientists like Galileo were nonconformists who proved old beliefs wrong. Artists like Dr. Seuss created wildly original books that publishers initially rejected. Inventors like the Wright brothers pursued ideas others thought impossible.
Being a nonconformist doesn't mean disagreeing with everything just to be different. True nonconformists think carefully about what they believe and why, then have the courage to stand by those beliefs even when it's uncomfortable. They're independent thinkers who value being true to themselves more than fitting in with the crowd.