Claim: The Boston Celtics share their arena with a baseball team.

The Boston Celtics -LRB- -LSB- ˈsɛltɪks -RSB- -RRB- are an American professional basketball team based in Boston , Massachusetts . The Celtics compete in the National Basketball Association -LRB- NBA -RRB- as a member of the league 's Eastern Conference Atlantic Division . Founded in 1946 and one of eight NBA teams -LRB- out of 23 total teams -RRB- to survive the league 's first decade , the team is owned by Boston Basketball Partners LLC . The Celtics play their home games at the TD Garden , which they share with the National Hockey League -LRB- NHL -RRB- 's Boston Bruins . The franchise 's 17 championships are the most of any NBA team , and account for 24.3 percent of all NBA championships since the league 's founding in 1946 . As a percentage of championships won , the Celtics are the most successful franchise to date in the major four traditional North American professional sports leagues .   The Celtics have played the Lakers a record 12 times in the finals , including their most recent appearances in 2008 and 2010 , where the Celtics have won nine meetings -LRB- but only two since 1980 -RRB- . Four Celtics players -LRB- Bob Cousy , Bill Russell , Dave Cowens and Larry Bird -RRB- have won the NBA Most Valuable Player Award for an NBA record total of 10 MVP awards . Their mascot ` Lucky the Leprechaun ' is a nod to the team 's Irish heritage and to Boston 's historically large Irish population .   The Celtics rose again after struggling through the 1990s to win a championship in 2008 with the help of Kevin Garnett , Paul Pierce , and Ray Allen in what was known as the new `` Big Three '' era , following the original `` Big Three '' era of the 1980s that featured Larry Bird , Kevin McHale , and Robert Parish .   After the end of the second `` Big Three '' era , general manager Danny Ainge began a rebuilding process with the help of new head coach Brad Stevens , who led the Celtics to a return to the playoffs in 2015 , 2016 , and 2017 . During the 2016 -- 17 season , the Celtics clinched the top seed in the Eastern Conference playoffs .