Let's talk about one of the most known gladiator in the not so clear number of gladiators: the raetiarius.
The raetiarius, or net fighter, was one of the most popular among the plebs and normal people (expacially women) and, instead, one of the most hated by emeperors and patricians. With no helm, or galeus, and no leg defenses, protected only by a iron or bronze shoulder defense, or galerus, and a hard leather manica covering only the left arm this gladiator was the opposite of the military virtues rappresented by the other fighters. Infact his tecnique was an hit and run style, keeping long distance from his opponent, the secutor, with his main weapon, the trident, and with his speed, so someone could address this fighter as a "coward", opposite to the murmillo, the secutor or the provocator.
In fact, the raetiarius did not descend from a particular etnic warrior, like thraex or secutor, and his tecnique was not used in the battlefields or in the army. Roman legionaries were instructed also by gladiators and learned their tecniques for using them in battle, but the "hit and run" style was totally useless for the legionaries.
It's not clear how the raetiarius came out. It's impossible to see him until the end of the first century A.D. or later. But from this point the net fighter will become one of the most popular gladiator in the arena and his pairring with the secutor or the scissor one of the most attended by people until the dawn of gladiatorial games.