1) Controversialist 2) Disputant 3) Eristic 4) Monkeywrench thrower 5) Obstructer 6) Obstructor 7) Resister 8) Thwarter 1) Naysayer 2) Obstructer 3) Obstructor 4) Resister 5) Stonewaller 6) Thwarter 
• (a.) Of or pertaining to obstructionists. • (n.) One who hinders progress; one who obstructs business, as in a legislative body.
Ob·struc'tion·ist noun One who hinders progress; one who obstructs business, as in a legislative body. -- adjective Of or pertaining to obstructionists. [ Recent]
[n] - someone who systematically obstructs some action that others want to take
obstructor noun someone who systematically obstructs some action that others want to take
someone who systematically obstructs some action that others want to take