In both the original and revised versions of the official guide book included with the 10th Anniversary Final Fantasy VII Ultimania, his character name is listed only as Reno. There are several surnames that fans have bestowed upon him (as previous comments have already mentioned), but none of them are canon.
Anyway! This is a really wonderful piece - And not just because it's Reno <3 - I really love the subdued colors and the subtle shadows across the knuckles of his left hand are amazing. Beautiful.