Tiaina Seau, Jr. (born January 19, 1969 in San Diego, California), known as Junior Seau, is an American Samoan NFL linebacker.

A two-position star at Oceanside High School, he met then-San Diego Chargers quarterback Dan Fouts at a promotion, who advised him to become a linebacker instead of a tight end.

Seau was an All-American at the University of Southern California and was the college teammate of Todd Marinovich and Rodney Peete, and was taken in the first round of the 1990 NFL draft by Bobby Beathard's Chargers.

Seau quickly became one of the most popular players on the team, receiving the nickname "Tasmanian Devil". His well-known "Lightning Bolt" dance (after the Chargers' logo) was particularly disliked by opposing teams, but well-liked by fans. He played in 12 Pro Bowls with the Chargers, and missed only two games in his first seven years of play. In every season with the team, he was the leading tackler. In 1991, he created the Seau Foundation, which raises money for drug awareness, child abuse prevention, and college scholarships. Seau also owns a clothing line, Say-Ow, as well as Seau's Restaurant in Mission Valley, San Diego.

In 2003, Seau was acquired by the Miami Dolphins in free agency, where he had another strong season. But a torn pectoral muscle in 2004 ended his season prematurely and in 2005 he hurt his ankle to end his season.

On March 6, 2006, Seau was released from the Dolphins to clear cap room.