The Boston Celtics sit firmly at the top, defined by a legacy of unparalleled excellence. As the most successful franchise in NBA history with 18 championships (as of 2026), the Celtics were the ultimate dynasty of the league's formative years. Most notably, they claimed 11 titles over a 13-season span between 1957 and 1969—a level of dominance that remains nearly impossible to replicate in modern professional sports. Compared to their perennial rivals, the Los Angeles Lakers, the Celtics have consistently set the benchmark for championship efficiency and defensive structure, remaining the ultimate measuring stick for greatness across every era.