The Boston Celtics (pronounced /ˈsɛltɪks/) is a professional basketball team based in Boston, Massachusetts, playing in the Atlantic Division of the Eastern Conference in the National Basketball Association (NBA). The team is owned by Wycliffe Grousbeck and coached by Doc Rivers, with Danny Ainge as the President of Basketball Operations. Founded in 1946, their 17 NBA Championships are the most for any NBA franchise. The Celtics' greatest domination came from 1957 to 1969, with 11 championships in 13 years, and eight in a row, the longest consecutive championship winning streak of any North American professional sports team. They currently play their home games at TD Garden.

The Celtics either dominated the league or played a large part in the playoffs in the late 1950s through the mid 1980s. After the deaths of the second draft pick Len Bias in 1986 and Reggie Lewis in 1993, the team fell into a steady decline, only making the playoffs four times from 1996 to 2007. The franchise has recently returned to prominence when Kevin Garnett and Ray Allen joined Paul Pierce during the 2007 off-season. On June 17, 2008, the Boston Celtics won their 17th championship by defeating the Los Angeles Lakers 4–2 in the 2008 NBA Finals. Four Celtics (Bob Cousy, Bill Russell, Dave Cowens, and Larry Bird) have won the NBA Most Valuable Player Award for an NBA record total of 10 MVP awards.