Pablo DeSoto
Pablo dislikes Necromancers, and blame them for most bad things that has happened in the last 20 years, including "that Diablo incident". Besides magic, he's knowledgeable about the areas surrounding Wortham and Tristram and has insights in how the Festering Woods work including its inhabitants, such as the Gnarled Walkers.
Abd al-Hazir's meeting with Pablo was the inspiration for the 20th entry in his writings.
Development
There is writings on upper left corner of the concept art picture of DeSoto indicating that he is been around at least from December 2006. Pablo DeSoto is also one of the few people named in the lore section of the official page. This indicates that Pablo DeSoto is an important character, most probably a NPC. This would make sense as the speculation is proven right about Leah being the daugher of DeSoto.