Kelly Bailey is a games composer. Bailey has been working with Valve Software and NVIDIA Lightspeed Studios. Bailey started in 1998 as the composer of Half-Life. After that, Kelly Bailey took part as the composer of Half-Life: Source. Bailey also worked on Half-Life 2: Episode One developed by Valve Software for PC, Android, macOS and Linux. The latest work of Kelly Bailey was Portal: Prelude, published in 2008.