BOSTON – Isaiah Thomas spent only two and a half seasons in Boston Celtics uniform, but during that short period of time he captured the everlasting endearment of an entire city, its beloved basketball team and its fanbase.

From his fourth-quarter heroics, to his postseason prowess, to his caring work in the community, the charismatic point guard put his body and soul into every aspect of his career with the organization.

IT’s tenure with the Celtics came to an end in the late summer of 2017 when he was dealt to the Cleveland Cavaliers as part of a trade package for Kyrie Irving. Monday night, more than a year and a half after the trade, the Little Guy with the big heart will finally be available to play his first game back in Boston, as a member of the Denver Nuggets.

Thomas’ highly-anticipated return will surely bring back fond memories, including a handful that we have highlighted in the list below. Here are Thomas’ top five most memorable moments in a Celtics uniform.

5. Perseverance in the Wake of Tragedy

Thomas’ character is defined by his inner strength and the ability to persevere through adversity. There was no greater example of his displaying of that trait than what took place April 16, 2017 – the first day of the Celtics’ postseason.

Less than 24 hours before tipping off Game 1 of the Eastern Conference quarterfinals against the Chicago Bulls, Thomas learned that his 22-year-old sister Chyna had tragically passed away in a car accident in their home state of Washington. He was devastated beyond measure, but he somehow mustered enough fortitude to join his teammates on the court at TD Garden the following night.

What followed was one of the most inspiring moments in the history of Celtics basketball.

Despite fighting back tears throughout the night, Thomas managed to lock in and score a game-high 33 points on 10-of-17 shooting. The C’s lost 106-102 in spite of the effort, but the unwavering commitment of their star point guard stood high above the state of defeat.

Thomas would go on to play every game of that postseason, leading the Celtics all the way to the Eastern Conference Finals, while playing in honor of his sister.

4. Becoming the NBA’s Top Assist Man Off the Court

Thomas didn’t just lead the Celtics in assists on the court during his tenure in Boston; he also led them in assists off the court.

Throughout his two and a half years with the organization, Thomas made it a top priority to give back to the Greater Boston community. His impact was so profound away from the game that, following the 2016-17 season, he earned the NBA Cares Community Assist Award, handed out annually to the player who displays the greatest commitment to his communities.

Some of his off-the-court highlights from that season included giving away 4,000 backpacks to students at the beginning of the school year, providing 3,600 meals in food relief efforts, impacting 200 pediatric patients involved in the Make-A-Wish Foundation, renovating a gymnasium in his hometown of Tacoma, Washington and launching the I.T. Helpdesk – a mass mentoring program for local youths.

For Thomas, making an impact outside of basketball was even more important than making an impact on the game itself. That is one of the many reasons why he was able to create such a strong bond with the Greater Boston community.

3. Proving the Doubters Wrong with First All-Star Nod

Thomas has played with a chip on his shoulder throughout his entire career. People always doubted him, believing that at 5-foot-9, he was too small to compete professionally.

In late January of 2016, he proved those doubters wrong by earning his first NBA All-Star nod.

Averaging 21.6 points and 6.6 assists per game at the time of his selection, Thomas became just the second player at his height or shorter to make the All-Star Game, joining Hall-of-Famer and one-time All-Star selectee Calvin Murphy. As the 60th and final pick of the 2011 NBA Draft, IT also became the lowest draft pick to earn an All-Star recognition since the league went to two rounds in 1989.

Thomas went on to tally nine points, three rebounds, an assist and a steal during 19 minutes off the bench for the East in what would be his first of two All-Star experiences. The highlight for him was having the opportunity to play against his idol Kobe Bryant in what was the Laker legend’s final All-Star game before retirement.

IT described the experience in its entirety as “everything I dreamed of,” for it finally gave him the elite recognition that he had been striving for his entire life.

2. The King in the Fourth is Born

Most NBA teams refer to the fourth quarter as “crunch time.” In Boston, the final 12 minutes action during the 2016-17 season became known as “Isaiah Time.”

Thomas carried the Celtics to countless victories thanks to his clutch scoring down the stretch, with the most memorable instance coming on Dec. 30, 2016 in a career performance against the Miami Heat.

The explosive point guard dropped 29 of his 52 points during the fourth quarter at TD Garden, where he led the Celtics to a nail-biting, 117-114 win over the Heat. He finished two points shy of Wilt Chamberlain’s 31-point fourth-quarter record and smashed the Celtics’ single-quarter scoring mark of 24 points that was previously shared by Larry Bird and Todd Day.

Remarkably, Thomas’ late-game heroics occurred on the second-night of a back-to-back. The Celtics arrived in Boston at roughly 3 a.m. that morning after playing LeBron James and the Cavaliers in Cleveland the night before. That didn’t stop IT from fighting through the fatigue and producing his first career 50-point effort.

Inspired largely by that effort, Thomas’ “King in the Fourth” nickname went viral around the world.

1. Fighting Tooth-and-Nail for 53 Points in Game 2 Win

Thomas battled through emotional adversity throughout the first round of the 2017 Playoffs after the sudden passing of his sister, Chyna. During the second round, he had to fight through physical adversity as well.

Unable to catch a break, Thomas had his left front tooth knocked out and fractured two others during Game 1 of the 2017 Eastern Conference Semifinals against the Washington Wizards, resulting in roughly 11 hours of dental procedures. None of that stopped him from suiting up and delivering a career-high 53-point effort in Game 2.

According to C’s coach Brad Stevens, Thomas was “not feeling good at all” heading into the May 2 contest, but the point guard discovered an emotional boost that pushed him through any physical pain he was enduring. Thomas’ will to play came from the spirit of his sister, who on that day would have been celebrating her 23rd birthday. He wanted to honor her by putting forth the best effort of his life.

Thomas shot 18-of-33 from the field, 5-of-12 from 3-point range and 12-of-13 from the free throw line to lead Boston to a 129-119 overtime win. Per usual, the All-Star took over late in the game, delivering 29 points during the fourth quarter and OT.

IT finished just one point shy of John Havlicek’s team playoff record 54 points, though he admitted that records were the last thing on his mind as he fought tooth-and-nail to drive his team to a win and a 2-0 series lead.

Amid the effort, Thomas proved that no obstacle was too challenging for him to conquer. He wore his heart on his sleeve and delivered the most impactful performance of an incredible season, as well as the most memorable moment of his career in Boston – one that has left Celtics fans inspired to this very day.