Gladiatrices (the singular is gladiatrix) are the female counterpart of male gladiators. They may have existed as early as Tiberius’s reign (14—37 CE), but their first documented appearance is in a gladiatorial event Nero sponsored in 66 CE. Despite their having been banned in about 200 CE, according to subsequent inscriptions that advertised their appearance, they continued to compete.
Some Romans were offended by them, seeing them as inappropriate in the hyper-masculine domain of the arena. Nevertheless, the proletariat was fascinated by them both as a novelty and a challenge to the social order and admired them for their courage and skill.
The most compelling evidence for their existence is the marble relief depicting the two gladiatrices that are pictured here (US Public Domain) and displayed in the British Museum. Their arena names, Amazon and Achillia, are engraved beneath them.
I'm busy working on my blog posts. Watch this space!