When you see a gorilla in a zoo, it's the western lowland gorilla.
In the wild there are also cross river gorillas (critically endangered), eastern lowland gorillas (endangered) and mountain gorillas (critically endangered). They can't be found in zoos, with the exception of the only two eastern lowland gorillas in captivity, living in Antwerp Zoo. The oldest one, Victoria, was born in the zoo in 1968 (back then they had more eastern lowland gorillas there). The youngest one, Amahoro, was born in the wild in/around 1990. I've been told (can't find anything about it on the net though) that she was smuggled out of her country to Belgium. When they found her in a box in a plane (if I'm correct), they confiscated her and brought her to Antwerp Zoo (she was about 4 years old back then). These two (beautiful!!!) ladies live with two western lowland gorillas, both females. The silverback (also western) died 8 January 2016.