Being a determinist i dont think i am capable of having regrets... having said that there are things i have done that still plague my mind... which technically i regret...
it is someone who believes that they are powerless to change thier destiny but I don't think that would play apart in regret you might not beable to change your destiny but you can still feel regret for bad things youv'e done....
A determinist is someone who believes that the universe was set in motion from the big bang and every action we ever make is a result of that, there is no possible way that anything could happen different from how it has.