Harry Spangler is a Paranormal Investigator, along with Ed Zeddmore. They had investigated a house when they heard the vase fall off the table. He gets stage fright. He is somewhat of a geek, liking Buffy and Lord of the Rings, plus playing RPGs.
Besides being on Supernatural for 5 episodes, the character Harry Spangler also played on "Ghostfacers" for 10 episodes.
The last name "Spangler" has also been spelled as "Spengler", to be closer to Egon Spengler from Ghostbusters, to whom his name refers.
When Harry makes a beeline back to the camper, Ed whispers, "Harry. Slow your roll buddy. They're gonna know we're excited." There is no way for Harry to hear Ed's whisper - he is too far away.