If you use
kill -9 and the processes don't die, they are likely in the process of dying, but are waiting on some system resource request to complete before they can proceed to die. You can try and find some dodgy method of trying to make them give up but the only guaranteed method is to restart the system. Your other choice is to leave them and hope they die on their own. Their are answers to a similar issue here that basically say the same, but I've never come across a sure-fire method to kill parasitic processes that won't die.
It may help if you know what they may be waiting on... if, for example, they are waiting on network file resources, you could try to unmount the nfs drive that they are waiting on. If you know anything further, you could try to artificially satisfy whatever it is they are requesting. Aside from that, there's not much else.