"Left Outside Alone" is a soul rock song written by American pop singer Anastacia and producers Dallas Austin and Glen Ballard for her third studio album, Anastacia (2004). It was released as the album's lead single in on March 15, 2004 (see 2004 in music) and reached number one in Australia, Austria, Argentina, Finland, Italy, Greece Spain, and Switzerland, number two in Denmark, the Dutch Top 40, the Euro 200 chart, Germany, Ireland, Norway, Romania, and the United World Chart, and number three in the United Kingdom. In the United States "Left Outside Alone" was another success on the Billboard dance charts, where it reached the top position on the Hot Dance Singles Sales.

Shot in January 2004 in California, the regular music video for "Left Outside Alone" was directed by Bryan Barber. There are actually three music videos for the song. The regular - first - version was for the worldwide market, excluding North America.

In the normal version, the video begins showing Anastacia singing the intro to the song on some sort of a bridge. After that, she is walking on a street and you can see a red poster of her on an advertising pillar. Then she gets in a car and drives away. During her drive, she is singing and looking to the car next to her, where she sees 'herself' kissing a man. Throughout the video, cuts of Anastacia in all these scenes are shown too. Later she gets out of the car and notices people dancing to her song on the street. While heading to a club, she opens a curtain, when a mysterious light is shining out.

The alternate version of this video, also known as "the blue-poster version", which is actually a video for the Jason Nevins Global Club Edit of the song, contains some editings, one of them being the fact that this version has a blue poster instead of the red one that is in the regular version also has a different ending.