Christopher Claus Andersen (born July 7, 1978) is an American former professional basketball player. Nicknamed "Birdman", Andersen was born in Long Beach, California, grew up in Iola, Texas, and played one year at Blinn College. Andersen began his professional career in the Chinese Basketball Association and the American minor leagues.

After getting called up to play in the National Basketball Association (NBA) from the NBA D-League, Andersen would go on to play for the Denver Nuggets and New Orleans Hornets. He received a two-year ban from the NBA in 2006 for violating the league's drug policy, but was reinstated on March 4, 2008, and re-signed with the Hornets the next day. He returned to Denver later in 2008, and remained with the team until 2012.

Andersen signed with the Miami Heat in January 2013 and won a championship with them that same year. He and Oliver Lafayette are the only Blinn students to ever play in the NBA. He most recently played for the Dallas Power in the Big3 league, helping them win the 2018 Big3 championship.

Andersen is the second of the three children of corrections officer and Danish immigrant Claus Andersen and Linda Holubec, a Tennessee native who worked as a waitress at the Port Hueneme naval base and played basketball in high school. In 1982, when Andersen was four, his family moved to Texas, using a loan from the Texas Veterans Land Board to purchase a 10-acre plot in unincorporated Iola, about 100 miles northwest of Houston. The Andersens then lived off the land, with Linda working in low-end jobs and relying on the help of neighbors and Linda's brother, who was a Navy supply boat captain. During Andersen's middle school years, he and his siblings were sent to a group home in Dallas for three years.

As a teenager, Andersen was convinced to take up basketball by the varsity basketball coach at Iola High School, Robert Stewart, who said the sport could give him a chance at a college scholarship. He was heavily recruited by the Texas A&M Aggies but did not have the necessary grades. Andersen instead signed an athletic scholarship to attend Blinn College in Brenham, where Stewart's father, Ernest, once served as athletic director. Andersen averaged 9 points, 7 rebounds and 7 blocks per game during the 1997–98 season. He led the National Junior College Athletic Association in blocks.

On October 9, 1998, Andersen committed to play for the Houston Cougars. During the fall semester at Blinn in 1998, he averaged 20 points, 10 rebounds and about 7 blocks per game. On January 8, 1999, Andersen left the Blinn basketball team to concentrate on his academics so he could meet eligibility standards. In May 1999, the Cougars announced that Andersen would not be eligible to play next season for academic reasons.

Convinced that he could play professionally, Andersen's high school coach arranged for him to play a series of exhibition games with the semi-professional Texas Ambassadors, and a game in China led Andersen to get an offer to join the Jiangsu Dragons of the Chinese Basketball Association.

In March 2000, Andersen joined the New Mexico Slam of the International Basketball League where he averaged just 1.1 points and 1.6 rebounds in six regular-season games and four playoff games.