The character Uncle Leo was introduced in 2:2 The Pony Remark, as one of the funniest peripheral characters of all time. Len Lesser, who would go on to portray this hilarious character, was wanted back by audiences the world round, and I still can't get enough of him.
Leo had a crime of passion, which was probably murdering someone who betrayed him 50 years ago by being an anti-semite who didn't say Hello. Being an old person, he steals things, yet obviously not anything expensive, because he needs to steal money from his sis, goes to an MD so bad (and therefore cheap), he's unlisted, can't support his mom over and above her very fixed income and hasn't moved down to Florida. He's extremely proud of Cousin Jeffrey, his son, who works for the Park's Department. He'll grab your arm and won't let go. Basically, he's my Uncle Leo, or to be more accurate, my dad's Uncle Leo. His name is Leo and everyone calls him Uncle Leo, he always holds your arm while talking to you, and looks and sounds exactly like TV Uncle Leo, and he's been this way for years before Seinfeld, which raises the question: How do LD/JS know my Uncle Leo? On a more serious postnote, my father's Uncle Leo just passed away. All kidding aside, he was a great man and I will miss him dearly.
Hello Uncle Leo = 19 (plus 1 Danny - 8:5 The Package)
(per episode except Cousin Jeffrey, Larry David, Farvman, and Lauren Bowles)
Uncle Leo = 14
Uncle Leo - 2:2 The Pony Remark
Uncle Leo/Jerry hug - 4:4 The Ticket