Former Employer Might Hurt My Career

My dedication to improve processes and make my workplace a better operation earned me the ire of my supervisors and got me fired. Now, I’ve heard rumors abound (some are REALLY awful), and I am afraid that these ill-meaning people will ruin my future. I would not even dignify these rumors by re-stirring the pot and contacting anyone of position back there, but when it comes to future employment, what can I do? What recourse do people like me have against potential slander and libel, when we just want to walk away dignified and continue with life?