Pauline (known as Lady in Japan) was the damsel-in-distress in the game Donkey Kong. She was, at the time, Mario's girlfriend; however, she is not a princess, just a regular woman. In the game, Pauline is kidnapped by the original Donkey Kong (who is now, in fact, the elderly Cranky Kong) and taken to a construction site. Of course, Mario, who was then a construction worker, must rescue her. As he climbs to the top of the construction site, Mario can collect various articles Pauline has dropped, such as her purse or hat, for bonus points. Pauline also made a cameo, a long with Mario, in the game Pinball.
Pauline has not been heard from since, as she has been replaced by Princess Peach as Mario's love interest. It is rumored that Pauline may be romantically involved with Stanley, but this is pure speculation. However, she has returned in Mario vs. Donkey Kong 2: March of the Minis.
Pauline was named after the movie serial, The Perils of Pauline. Much like her video game counterpart, the movie character Pauline constantly gets kidnapped.
In the Super Mario Brothers Movie there is a character named Daniella who is Mario's girlfriends; Daniella is based on Pauline.
She appears in Mario vs. Donkey Kong 2: March of the Minis, where she gets kidnapped by Donkey Kong. Mario of course, has to save her but with the help of Mini-Marios. Since the game takes place in the Mushroom Kingdom, it is unknown what Peach would say about Mario saving Pauline.
It is guessed that she will possibly appear in Mario Party 8 along with Baby Mario.