The teller was the Off-Track-Betting cashier at the beginning of the Season 2 episode Deception. He was portrayed by actor Rod Britt.
Just before the start of the race, the teller is trying to deal with the Fat Man, who didn't understand how to bet. He was holding up the line until Anica Jovanovich explained to the teller what the man wanted to bet on. That allowed Gregory House to place his bet just as post time arrived, but they weren't quick enough for Anica to place her own bet.