Trillian is a proprietary multiprotocol instant messaging application for Windows, Mac OS X, Android, iOS, BlackBerry OS, and the Web, created by Cerulean Studios. It can connect to multiple IM services, such as AIM, ICQ, Windows Live Messenger, Yahoo! Messenger, IRC, Novell GroupWise Messenger, Bonjour, XMPP, and Skype networks; as well as social networking sites, such as Facebook, Twitter and MySpace; and email services, such as POP3, IMAP, Gmail, Hotmail and Yahoo! Mail.
Initially released July 1, 2000, as a freeware IRC client, the first commercial version (Trillian Pro 1.0) was published on September 10, 2002. The program was named after Trillian, a fictional character in The Hitchhiker's Guide to the Galaxy by Douglas Adams. The old version of the official web site even used to have a shrine to Douglas Adams on its front page.
On August 14, 2009, the prior major release of Trillian for Windows, named Trillian Astra (4.0), was launched, along with its own Astra network. Trillian Astra has a free version, and a premium version with extra features.
On November 18, 2009, the first mobile version of Trillian was launched for iPhone. As of 2010, final builds for Android, BlackBerry, and Apple iOS were available for their markets (Market, App World and App Store respectively) was $4.99 USD. Trillian was initially a paid app but is now free of charge.
Trillian 5 for Windows was released in May 2011.