Daniel Steven Kowalski (born 2 July 1975) is an Australian former middle- and long-distance swimmer specialising in freestyle events.
He competed in the Olympic Games in 200-, 400- and 1,500-metre individual freestyle events and in the 4 × 200-metre freestyle relay.
At the 1996 Summer Olympics, he was the first man in 92 years to earn medals in all of the 200-, 400- and 1500-metre freestyle events.
Kowalski, alongside Livinia Nixon, hosted the short-lived TV show Plucka's Place in 1997.
Kowalski is perhaps best known for being perpetual runner-up to fellow Australians Kieren Perkins and Grant Hackett, who were, respectively, the world's best 1500-metre freestyle competitors during the earlier and later parts of Kowalski's career, particularly when compared to Kowalski.
He was an Australian Institute of Sport scholarship holder.