Ellen McLain is an opera singer and voice actress from Nashville, Tennessee, USA. She provides the voices of many characters in several video games from Valve. Among them are GLaDOS, the artificial-intelligence antagonist in Portal (2007) (for which she won an AIAS Interactive Achievement Award for Outstanding Achievement in Character Performance) , Portal 2 (2011), and Lego Dimensions (2015), the announcer in Team Fortress 2 (2007), and the voice of the Combine over-watch of the Half-Life 2 (2004) series, and recently, the voice of one of Delamain's cabs in Cyberpunk 2077 (2020). McLain is the only person whose voice is in all of the Orange Box games.

McLain sang "Still Alive," the ending-credits song of Portal, and "Want You Gone," the ending-credits song of Portal 2. Both were written by Jonathan Coulton. She also sang the opera-style turret song featured at the end of Portal 2, which is referred to by fans as the Turret Opera.

McLain is married to John Patrick Lowrie, a fellow voice actor, who also worked on the video games Half-Life 2 and Team Fortress 2. In the former, her husband voiced a citizen who assists the protagonist. In the latter, he voiced the Sniper.