The Miami Heat were founded in 1988, but they quickly made an impact on the league, and their rivalry with the Boston Celtics was birthed in the mid-2000s.
This has not been a traditional rivalry, but it's one that has been built through the playoffs and player movement. There are multiple names that weren't superstars but played key roles on championship teams.
Let's start with the most iconic player who shifted teams.
Ray Allen (1996-2014)
The former SuperSonics All-Star made his way to Boston via trade. Seattle traded Allen and Glen Davis, the 35th overall pick in the 2007 NBA Draft, to the Celtics in exchange for Delonte West, Wally Szczerbiak, and the fifth overall pick, Jeff Green. The move convinced Kevin Garnett to drop his no-trade clause and allow and Celtics-Minnesota Timberwolves trade to happen.
Allen developed his game into more a sharpshooter role to mix with Garnett and Paul Pierce, and the trio helped the C's win the 2008 NBA Finals. The "Big Three" era lasted for five seasons until Allen grew frustrated at having his name involved in trade rumors, and a reported bench role and internal tension with Rajon Rondo led him to sign with the Heat on a mid-level exception.
Celtics fans were not happy, especially due to the fact he was joining another "Big Three" in LeBron James, Dwayne Wade and Chris Bosh. Allen didn't start, but he was a perfect fit in Miami's offense. He hit one of the most iconic shots in NBA Finals history in 2012 with a Game 6 shot that sent the game into overtime. The Heat went on to the win the title, which made Allen a two-time NBA champion.
Antoine Walker (1996-2012)
The Kentucky product was drafted with the sixth overall pick in the 1996 NBA Draft. Boston still was struggling in the post-Larry Bird era, and despite Walker making All-Rookie First Team, the Celtics finished with the worst record in the NBA. Walker was one the of the few players who thrived in the Rick Pitino era -- him being his former college coach certainly didn't hurt.
The team got better after Paul Pierce was drafted in 1998, and he and Walker became the Celtics' core duo until the latter was traded to the Dallas Mavericks at the start of the 2003-04 season. Walker returned to Boston in 2005 through a mid-season trade, and he was traded to Miami the following offseason as part of a five-team trade. He joined a team that had Wade and Shaquille O'Neal as its pillars, and Walker became a key 3-point threat for a team that went on to win the title.
It was a fact Celtics fans were bitter about since they felt he should have done it with Pierce, but luckily for them, Boston won the title season two seasons later.
James Posey (1999-2011)
Posey also was on the 2005-06 Heat team that won the NBA title and, like Walker, played a key role as a shooter and defensive threat. Also similar to Walker, the wing arrived to Miami in that five-team trade. After two seasons with the Heat, Posey signed with the Celtics, and he fulfilled the same role he did with Miami: Play good defense and hit timely buckets. He also was pivotal in guarding small forwards and power forwards as a stretch-four during a time when that was not a popular strategy. Like Allen, Posey became a two-time champion with Miami and Boston.
P.J. Brown (1992-2008)
Sticking with that 2007-08 Celtics team, Brown also was a key contributor off the bench for Boston. But prior to his arrival in Boston, he played four seasons in Miami from 1996-2000. He made All-Defensive Second Team three times during his career with the Heat, and he brought a toughness to a Pat Riley team that already had a lot of it, especially during his fight against New York Knicks guard Charlie Ward in the 1997 playoffs.
Pierce and Allen convinced the big man to sign with the Celtics in the middle of the season, and while he was there for defense, he had a breakout in Game 7 of the Eastern Conference semifinals when he scored 10 points and six rebounds against the Cleveland Cavaliers. His six fourth-quarter points helped Boston reach the NBA Finals, and he retired as an NBA champion.
Eddie House (2000-2011)
The last stop on the 2007-08 Celtics title team takes us to House. The Arizona State product was taken in the second round of the 2000 NBA Draft. He was a player ahead of his time with his efficiency from 3-point range. However, his 6-foot-1 frame was not something valued during that era, but it became vital when he signed a one-year deal with the Celtics. He hit timely shots that helped Boston win the NBA title in 2008. House re-signed with the Heat in the final year of his career, but he was unable to become a two-time champion as Miami lost in the 2011 NBA Finals to the Dallas Mavericks.
Kelly Olynyk (2013-present)
The Canadian big man was drafted by the Mavericks in the 2013 NBA Draft before he was soon traded to the Celtics. Olynyk struggled with injuries during his tenure in Boston, and he became infamous for his role in Kevin Love's shoulder injury in the 2015 NBA playoffs. However, when he did play, Olynyk was a reliable 3-point shooter that blended in well in Brad Stevens' offense.
But Boston renounced his rights, and he signed with the Heat. He served a similar role in Miami, and even played in more games there than he did with the Celtics. Olynyk helped the Heat reach the 2020 NBA Finals, where they lost to the Los Angeles Lakers.
Honorable mentions: Jae Crowder, Shaquille O'Neal, Brian Shaw
Crowder also was on the 2019-20 Miami team, but he only came on during the middle of the season, and that was the only year he played for the team. O'Neal's late-season ring-chasing tour stopped in Boston for the 2010-11 season, which was his last of his NBA career. Brian Shaw was drafted by the Celtics, but his contract dispute with the team has became an infamous legal case, and his time in Miami was not very memorable.
