maverick (n.)
A maverick is an independent person who does not follow the group.
The word comes from Samuel A. Maverick, a nineteenth-century Texas landowner. Unbranded cattle associated with him came to be called mavericks, and the word spread through cattle country for unbranded animals.12
By the end of the nineteenth century, the word was also being used for people who went their own way.12
She was a maverick in her field.