How do you deal with toxic colleagues in workplace?

I think it depends on what type of toxicity they exhibit. If they've done something to break company policy, then obviously the best way to handle them is to document and report. Keep a record of their documents to submit to HR. However, it can be tougher dealing with those that are toxic but aren't breaking any rules. If this is the case, then I would suggest avoiding contact with them unless it's absolutely necessary. Once they get the message they'll eventually leave you alone.