Step 1 : Introduction to the question "Which TV comedy series features Felix Unger and Oscar Madison?"
...Felix Unger, played by Tony Randall, is a complete neat freak. Oscar Madison, played by Jack Klugman, is a slob of the worst order. When divorce hits them both, they find themselves in need of someone to share an apartment in New York City. These two men become "The Odd Couple." Felix is the fussy photographer who borders on OCD. Oscar is a sportswriter and 'sloppy' is putting it mildly. The two argue like an old married couple, which is hilarious and endearing at the same time. The popular series ran for five years. Source: IMDb.com