It's a despective word, so I wouldn't translate it as pal, mate etc, because as far as I know, these words in English don't have any pejorative meaning, do they?
>Koleś is short and colloquial for kolega (colleague or friend).
I'd never say to my friend "koles". I'm not even sure whether it is true that it is colloquial for "kolega". It is much less respectful than "kolega". Of coure a lot depend on the context and you can say with sort of respect "Ten koles tam to dopiero przystojniacha", where it is used more like "bloke, guy" but usually it means something like "geezer" but mostly about younger people...
This something I agree with (e.g. fajny koleś) and judging form Katie's resposne, I think these would be fine translations:I agree with you that you wouldn't use koleś in the same way as kolega though etymologically it derives from it. I'd say that it's mostly used when speaking about some guy in the third person and not when addressing him directly. It still doesn't have to be disrespectful, as you said it depends on the context.
Guy was my guess before I read the thread.[...]
Guy and Dude are used to talk about some random man, for example. There was this guy in the pub.... Other words along the same lines are chap, bloke, geezer. man, lad (if he's young or you come from my locality) (Kid is used in the same way, for a child or young man if you live in Yorkshire).
Dude is an american word, which is catching on here amongst the younger ones. Middle aged people and older people wouldn't normally use that expression.