Winamp — Popular Extensible Music Player

Winamp — It really whips the llama’s ass!

The classic alternative to Window Media Player. Winamp is a cross platform, extensible, free and skinnable media player with a large community and a long past. Development has stopped, but may start again, meanwhile, the development community has largely moved to Foobar2000.

Website
Download
Wikipedia

Android / Mac / Windows
Freeware