In English you usually use ''haha'' and any infinite reproductions of that combination like hahahhahahaha. Some variations include: hehehhe hihihihi (for girls mostly, or when trying to be cute) hohohoho (which sounds more like santa claus) huhuhuhu (I don't believe this one is used) Whahah (when you just want to add that extra little bit of comical effect. It can also be written with some more variation such as: bahahah or phahaha

I would also like to add the sound of evil laughter to this list: Muahahahaha!