GIANT AntiSpyware was a spyware detection and removal application developed by GIANT Company Software, Inc.

GIANT Company Software, Inc. was acquired by Microsoft Corporation on December 16, 2004. GIANT AntiSpyware is no longer sold and Microsoft stopped releasing spyware definition updates for it in August 2006.

Microsoft's Windows Defender (formerly Microsoft AntiSpyware) program is built upon a restructured version of GIANT AntiSpyware.