On July 9th, 1981 Donkey Kong hit arcades. It was in this original Nintendo arcade game that both Donkey Kong and Mario (at the time named Jumpman) were born.
There have been a lot of changes since then. Mario is no longer a carpenter on a construction site (he became an italian plumber traversing the NYC plumbing system in Mario Bros). Donkey Kong is no longer Mario's arch nemesis (Bowser assumed that role in Super Mario Bros. as King of the Koopas). And the damsel in distress is no longer Pauline (she was replaced by Princess Daisy who was later replaced by Princess Peach).
With over 200 titles it is without doubt that Mario is the most iconic video game character of all time.
Prima Games celebrates his birthday in a few article I think you guys will enjoy:
Happy Birthday Mario & Donkey Kong!
15 Greatest Moments in Mario History
This is What Mario Looked Like in the Original Donkey Kong
The History of Mario Kart