Also look here.
Maverick
As you know, a maverick can be an unbranded calf (after Samuel
Maverick, a cattleman who seems to have neglected such branding) or
someone who defies customary thought and practice. I assume you
mean the second definition.
Since maverick is derived from a proper name there is no direct
translation.
However, you could use a synonym such as "free mind"
liber animus.