Mr. Feldman is a person who is seen jogging in the Griffin's neighborhood in "Must Love Dogs".
As Chris prepares to take Stewie to a place where Peter can't find what's left of his Halloween candy, he is unable to tell him of the location, noting that there are ears everywhere. He then greets Mr Feldman across the street, who overheard that they were taking a little trip, which Chris dismisses.
Mr. Feldman is also in attendance at Quagmire's engagement party to Carrie, noting that he's heard good things about Quagmire.