Joe Marcus Johnson (born June 29, 1981) is an American former professional basketball player. Nicknamed "Iso Joe", he played college basketball for the Arkansas Razorbacks. After two years with Arkansas, he declared for the 2001 NBA draft where he was drafted 10th overall by the Boston Celtics.

Johnson was a seven-time NBA All-Star and also played for the Phoenix Suns, Atlanta Hawks, Brooklyn Nets, Miami Heat, Utah Jazz and Houston Rockets, while also representing the United States national team. While playing for the Hawks, he earned the nickname "Iso Joe" for his skills on isolation plays. He is one of 52 NBA players to score 20,000 career points. At the time of his retirement, Johnson was the last active player in the NBA to have shared the court with Michael Jordan.

Born in Little Rock, Arkansas, Johnson was a member of the William E. Thrasher Boys & Girls Club as a child and attended Little Rock Central High School, a school that had produced other professional athletes including Baseball Hall of Famers Brooks Robinson and Bill Dickey, as well as football player Fred Williams and collegiate football coach Houston Nutt. In his senior year, he led the Tigers to a state title, averaging 18.5 points, 7.8 rebounds, and 5.2 assists, and was named Arkansas Mr. Basketball.

In his freshman season at Arkansas in 1999–2000, Johnson was named to the SEC All-Freshman team and SEC All-Tournament team after averaging 16.0 points, 5.7 rebounds, 2.2 assists and 2.0 steals per game. Johnson led Arkansas to the 2000 SEC men's basketball tournament championship.

In his sophomore season in 2000–01, Johnson was named to the All-SEC second team and SEC All-Tournament team, while also receiving honorable mention All-American honors. In 30 games, he averaged 14.2 points, 6.4 rebounds, 2.6 assists and 1.4 steals per game.

Following his sophomore season at Arkansas, Johnson declared for the 2001 NBA draft where he went on to be selected with the 10th overall pick by the Boston Celtics. Through the first half of the 2001–02 season, Johnson played 48 games for the Celtics and made 33 starts, as he averaged 6.3 points, 2.9 rebounds and 1.5 assists per game. He was later traded to the Phoenix Suns on February 20, 2002, along with Randy Brown, Milt Palacio and a first-round pick in exchange for Rodney Rogers and Tony Delk.

Johnson became a force with Phoenix as he averaged 14.0 points per game in his three and a half seasons with the Suns, becoming a clutch three-point shooter as he averaged 39.3% from the three-point arc during his tenure with the Suns.

During the 2004–05 campaign, Johnson and the Suns posted a 62–20 record. Johnson's three point accuracy improved dramatically between 2004 and 2005, shooting 30.5% on threes in 2004 and 47.8% in 2005, and shooting .556 in the 2005 playoffs. In the 2005 NBA playoffs, Johnson required surgery to repair a left orbital bone fracture sustained following a dunk attempt against the Dallas Mavericks in the second round. Johnson missed the remainder of the series against the Mavericks as well as the first two games of the Western Conference Finals against the San Antonio Spurs. When he returned, Johnson wore a face mask for protection. The Suns fell to the eventual NBA champion Spurs, 4 games to 1.