Lightning rod
From RationalWiki
A lightning rod is a person who espouses a particularly strong version of some (usually) political idea, in order to attract the energies and efforts of the opposition. They are not taken seriously by the more moderately positioned people on their own side, but are appreciated for the distraction they provide.
One well-known person sometimes referred to as a lightning rod is Ann Coulter. Another is the Rev. Al Sharpton.
