Unlike fake cat people like the science origin Bobcat, Cat Man is a real cat person. He is a man well-integrated into society, going in to work every day and paying his bills, but he is also a cat with all the hyperactivity, play aggression, and 15-hour sleeping period. He frequently dozes off during meetings and ambushes shareholders, but he gets away with it due to cat privilege.
He keeps all his net-worth in cash in teetering piles around his penthouse. One day, while he was napping, a breeze stirred into a storm and blew all his money out the window. He woke too late to do anything but spectate. As his last dollar floated away, he erupted into a low moan heard throughout Nova Praetoria:
Now, by day, he roams the city, scavenging enough of his old money to afford next month's rent. If you find any loose dollars in the street, you must return them to Cat Man. It is his money.
Then at night, he moonlights as a superhero. He works closely with the press to ensure maximum coverage of his heroics. When asked his motivations, he always asserts he does it all for the attention. His powers are pretty standard for a cat: claws, reflexes, and stealth.