|Dates||???? - 2013 (mauled by The Colonel and a pack of dogs)|
|Episode(s)||9.05 Dog Dean Afternoon|
Leo was the Head Chef/owner of Avant-Garde Cuisine. He was diagnosed with Stage IV carcinoma, and was way past the point of conventional treatment, until he met a Pawnee shaman who showed him a cure through the use of shamanism. The spells he used meant he took on the physical characteristics of the animals whose organs he consumed. However, the effects were only temporary, which resulted in his experimentation in "combination therapy," which made him stronger and caused the effects to last longer. When he witnessed Sam heal from a slit throat (due to Sam currently acting as the Vessel for the angel Ezekiel), Leo planned to eat Sam in the hope of gaining his healing powers, but Dean was able to turn the tables on him by summoning a pack of dogs that he had released from an animal shelter earlier to attack Leo, defeating him for good.