The Atlanta Thrashers were a professional ice hockey team based in Atlanta. Atlanta was granted a franchise in the National Hockey League (NHL) on June 25, 1997, and became the league's 28th franchise when it began play in the 1999–2000 season. They were members of the Southeast Division of the NHL's Eastern Conference, and played their home games at what is now known as State Farm Arena in downtown Atlanta. Despite several high-level draft picks and some high-profile player acquisitions, including two first-overall selections, the Thrashers were futile for the majority of their existence. They qualified for the Stanley Cup playoffs only once, after winning the Southeast Division in the 2006–07 season, but were swept in the first round by the New York Rangers.

In May 2011, the Thrashers were sold to Canadian-based ownership group True North Sports & Entertainment. The group moved the franchise to Winnipeg, which became the second incarnation of the Winnipeg Jets (the first incarnation of the Winnipeg Jets relocated to Phoenix in 1996 to become the Coyotes). The sale and relocation was approved by the NHL on June 21, 2011. With the sale and relocation of the team, Atlanta became the first city in the NHL's modern era to have two ice hockey teams relocate to different cities. In both cases, the team moved from Atlanta to a Western Canadian city; the city's previous NHL team, the Atlanta Flames, moved to Calgary in 1980 to become the Calgary Flames.

After the departure of the International Hockey League (IHL)'s Atlanta Knights (1992–1996) to become the Quebec Rafales, the city of Atlanta was awarded an NHL franchise on June 25, 1997, as part of a four-team tiered expansion. This also included teams in Nashville, Columbus, and St. Paul, in which each new franchise would begin play as its respective new arena was completed. The birth of the new franchise marked NHL hockey's return to Georgia after the Atlanta Flames, established in 1972, departed for Canada in 1980 to become the Calgary Flames. The Flames had been the League's first foray into the southern U.S., and their failure discouraged further efforts to bring NHL hockey south of Washington for another decade.

The nickname "Thrashers," after Georgia's state bird, the brown thrasher, was selected from a fan poll. "Thrashers" had actually been runner-up to "Flames" in the poll (as an homage to the old Atlanta Flames), and Philips Arena, the Thrashers' new home, was built on the site of the former Omni, which had been home to the Flames. By coincidence, the first encampment (circa 1839) which later became Atlanta was called Thrasherville, and a historical marker of this is located just down from the arena in front of the State Bar of Georgia (the former home of the Federal Reserve Bank of Atlanta). The team was owned by Atlanta-based media mogul Ted Turner, who also owned Major League Baseball's Atlanta Braves and the NBA's Atlanta Hawks.

The newly formed Thrashers selected Patrik Stefan with the first overall selection and Luke Sellars with the 30th overall pick (second pick of the second round) in the 1999 NHL entry draft. However, the entire 1999 NHL entry draft was a major disappointment for the Thrashers, as all 11 of their draft picks were out of the NHL by the team's last season; Stefan played the most games for the Thrashers (414) from that draft. Their first two picks (Stefan and Sellars) were two of the biggest disappointments in draft history; NHL.com listed Stefan as the worst first overall pick of all time and Sellars (who played only one NHL game) as the worst 30th overall pick in NHL history. This was a surprise, as not only did the media hype Stefan as a franchise player, but hockey experts also considered then-Thrashers general manager Don Waddell to have excellent scouting ability.

The Thrashers played their first game on October 2, 1999, losing 4–1 to the New Jersey Devils. Captain Kelly Buchberger scored the franchise's first goal in the loss and the team finished their first season in last place in the Southeast Division with 14 wins, 61 losses (including four overtime losses), and seven ties for a total of 39 points.

Atlanta had the second overall pick in the 2000 NHL entry draft; this draft brought better results, as the player chosen with that pick, Dany Heatley, became one of the team's best players. The team also had a fine choice in the 2001 draft with first overall pick Ilya Kovalchuk. Both Heatley and Kovalchuk played their first season in the NHL in 2001–02; both were named to the NHL All-Rookie Team and Heatley was awarded the Calder Memorial Trophy as the League's Rookie of the Year.

The early years of the Atlanta Thrashers saw a sharp increase of hockey fans in Atlanta. Ticket sales for Thrashers games averaged at 10,000 per night, many of them being season tickets. A section of the arena was dedicated to season ticket holders that called themselves the "Nasty Nest". The "Nasty Nest" chanted and shouted at the opposing team to disrupt them. The Thrashers also had two Thrasher bird heads that faced opposite to the scoreboard. The Thrasher heads opened their beaks to reveal a flamethrower that ignited when the team scored a goal. At this time, the franchise adopted a motto "Believe in Blueland", which was often used in advertising.