Third on our list…. the Secutor.
“The first thing to note about the secutor is the name: meaning ‘chaser, pursuer’, it hints at the reason for this particular gladiator’s existence. Otherwise known as the contraretiarius, the secutor fought the retiarius; it is thought that the category was specially created for that purpose; if that origin is authentic, then there is some justification for thinking that the secutor was an offshoot of the murmillo.
In a nutshell, the arms and armour of the secutor were the same as those of the murmillo, and only the form of the helmet differed; it was brimless and had only a low, smooth, featureless crest following the curve of the bowl. The back of the helmet curled into a small neck-guard. Unlike other helmets with metal grilles forming the upper half of the visor, the secutor helmet enclosed the face completely; the visor had only two small eyeholes, each a scant inch (3 cm) in diameter, and although it was hinged to open from the side, it had a catch on the exterior to ‘lock’ the gladiator in it.”
See also: http://en.wikipedia.org/wiki/Secutor