Just as in other genres there are two well respected developers that produce the majority of titles.
Capcom are the best known for the [Street Fighter]? series which has spawned dozens of versions, but made famous by Street Fighter II and Street Fighter II CE. Since then subsequent incarnations have seen the roster of fighters evolve and swell, leaving at times, just the main two characters, Ryu and Ken from the original Street Fighter II line up. This is typical of the evolution of a fighting game series.
Contrasting with Capcoms approach is SEGAs AM2? developers, the Virtua Fighter series has seen just three and a bit versions since its inception in (year?). Each new installment brings with it years of carefully refined mechanics, style and gameplay and is always a big event.