Steve Irwin really was a hero.

Terri Irwin celebrated National Superhero Day by sharing a photo of her late husband to Twitter, with the sweet message, "Celebrating my #NationalSuperheroDay."

WATCH: Bindi Irwin Channels Her Late Father During Crocodile Feeding at Australia Zoo

Steve's heroism, of course, was in how he inspired countless people around the world to take an interest in wildlife as the beloved host of The Crocodile Hunter, before the conservationist tragically died from a stingray encounter in 2006 at age 44 while filming an underwater documentary.

Last year, Terri admitted that she hasn't dated anyone since her husband died.

RELATED: Bindi Irwin Pays Tribute to Her 'Crocodile Hunter' Father 10 Years After His Death

Watch the video below to find out why.