The Starship Enterprise may boast a proud legacy, but Star Trek's greatest ship is the Excelsior. Created by Gene Roddenberry, Star Trek: The Original Series and Star Trek: The Next Generation are about the exploits of the starships named Enterprise commanded by Captain James T. Kirk (William Shatner) and Captain Jean-Luc Picard (Patrick Stewart); there was also the prequel Star Trek: Enterprise starring Captain Jonathan Archer (Scott Bakula). The franchise has also spotlighted other popular starships like Star Trek: Deep Space Nine's U.S.S. Defiant and the titular vessels of Star Trek: Voyager and Star Trek: Discovery. However, the U.S.S Excelsior and the Excelsior-class starships are the true backbone of Starfleet.
The U.S.S. Excelsior was introduced in Star Trek III: The Search For Spock, which was set in 2285. Dubbed "The Great Experiment", the Excelsior (NCC-2000) was larger and more advanced than the Enterprise and it was to be the first starship equipped with a transwarp drive. However, Montgomery Scott (James Doohan) sabotaged the Excelsior to allow Kirk and his crew to steal the Enterprise and escape to resurrect Spock (Leonard Nimoy). Regardless, the Excelsior's transwarp drive turned out to be a failure because of the instability it caused to dilithium crystals. After spending the next few years in spacedock, the Excelsior finally launched on a three-year mission under the command of Captain Hikaru Sulu (George Takei) cataloguing gaseous anomalies in the Beta Quadrant. In Star Trek VI: The Undiscovered Country, set in 2293, Sulu led the Excelsior to aid Kirk's Enterprise in exposing a conspiracy to prevent the peace treaty between the Klingons and the Federation.
Originally, Star Trek producer Harve Bennett intended for Kirk and his crew to take command of the Excelsior. The Enterprise was destroyed in Star Trek III and the idea simply was that Kirk would get the Excelsior as his new ship. However, those plans were changed, largely due to the producers fearing fan backlash because Star Trek and Kirk are synonymous with the Enterprise. Instead, at the end of Star Trek IV: The Voyage Home, Kirk took command of the U.S.S. Enterprise-A, which was an identical Constitution-class vessel. But as the franchise continued in the 24th century with Star Trek: The Next Generation, the Excelsior-class starship quietly took on a greater significance as the most important starship class in Starfleet.
The Excelsior-class starship debuted in the 23rd-century but, remarkably, they are still a key part of Starfleet in the 24th century. Indeed, Excelsior-class starships fought in Star Trek's major wars such as against the Borg in the Battle of Wolf 359 in 2366-2367 and the Dominion War of 2373-2375. This means that, even though the idea of transwarp drive was scrapped long ago, the Excelsior-class ships have been active in Starfleet for almost an entire century. Further, Starfleet admirals and flag officers typically use Excelsior-class ships as their personal flagships.
Along with the U.S.S. Excelsior - a newer version with the registry NCC-21445 is active in the 24th century - other famous Excelsior-class starships are the U.S.S. Hood and the U.S.S. Potemkin (Commander Will Riker served on both ships prior to the Enterprise-D), the U.S.S. Crazy Horse, the U.S.S. Gorkon, and... the U.S.S. Enterprise-B. As seen in Star Trek Generations, Captain Kirk was presumed killed by the Nexus on the maiden voyage of the Enterprise-B. Although the Enterprise-B's tenure under Captain John Harriman (Alan Ruck) was relatively undistinguished compared to Archer, Kirk, and Picard's vessels, becoming part of the Enterprise's legacy enhanced the Excelsior-class' status within Starfleet.
The Excelsior-class' sleek design, with its curved warp nacelles, is also the forebearer of the Galaxy-class starships like the U.S.S. Enterprise-D. And, although the Excelsior-class starships were never featured as the signature vessel of a Star Trek series (Sulu is the most famous Captain of the Excelsior), the Excelsior has proven itself to be the most important starship class of the franchise. After all, despite its enduring legacy and status as the flagship of the Federation, there is no Enterprise-class of starships in Star Trek.