Shannen Rossmiller, (born May 31, 1969), is an American lecturer and instructor in cyber counter-intelligence forensics and a former Montana municipal court judge who has had a controversial role as a vigilante online terrorist-hunter, and who was once part of the 7Seas group.
A former high school cheerleader, paralegal, and a mother of three, Rossmiller posed online as militant anti-American Muslim radicals to attract the eye of those with similar mindsets. While still a member of 7-Seas group, she provided evidence that led to the arrest and conviction of Ryan G. Anderson, a National Guardsman who was about to deploy from the U.S. to Iraq. Ryan is now serving a life sentence for seeking to aid the enemy during a time of war and attempted espionage.
In 2005, while posing online as an Al Qaeda financier, Rossmiller offered the transient Michael Reynolds $40,000 to purchase fuel trucks to attack American pipelines. Reynolds was arrested when he attempted to pick up the money. In 2007, he was convicted by a jury of attempting to provide material support to Al Qaeda and related charges, and sentenced to 30 years in jail.
As of July 2007, a publicist was seeking a book or movie deal based on Rossmiller's story,  and in 2011 she published a book entitled The Unexpected Patriot.
- Shannen Rossmiller "Biographical information", "KXMB.com", July 19, 2007.
- "Hon. Shannen L. Rossmiller (Ret.), Cyber Operative and Co-founder, AC-CIO, LLC", January 6, 2009
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- Shannen Rossmiller, "My Cyber Counter-jihad", Middle East Quarterly, Summer 2007
- Sanders, Eli. "Guardsman Given Life in Prison for Trying to Help Al Qaeda", The New York Times, September 4, 2004.
- McGinn, George."American Convicted Of Attempting To Aid Al-Qaida Sentenced To 30 Years", "AllHeadlineNews.com",November 8, 2007.
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- Tremonti, Anna Maria. "CBC The Current", June 15, 2006.
- Dempsey, John."Biz zeroes in on real-life terrorist hunter: Rossmiller story makes Hollywood rounds", Variety, July 20, 2007.