My sister once had a French teacher who's last name was Walbert - he was a horrible teacher (well, his French was horrible at least, so she did not really learn very much and thus won't be of any help to me when we go to DLP!)
Walter is very much a Germanic name I think and I just looked it up in the German wikipedia. It originates from the words: ruler and army. And they had forms of the name in other languages, unfortunately no Spanish, but French: Gauthier, Gautier, Gaucher and Italian: Gualtiero. Do any of these sound similar to a Spanish name??
Ok, searching around in the entry for Walter in other languages, the Dutch version had the following Spanish names: Gutierrez, Guterres Who would have guessed that???