The Z-95 Headhunter was a standard starfighter during the rise of the Palpatine Empire.
The Z-95 was an everyman's fighter; Cheap, light, easily upgradeable, fast, easy to work on, and a large parts market. Practically every faction that WAS a faction used Z-95s, with the exception of the Empire. It was introduced just prior to the Clone Wars, during a brief partnership between Incom and Subpro, but when the partnership ended, Incom gained the Intellectual Property to the Z-95. It has many, many variations on the same basic airframe, including but not limited to; Reconnaissance variations, beefed-up heavy fighters, hyperspace-capable versions, light bomber craft, and even a heavily modified Clone variant that saw wide use in the Clone Wars as a multi-role combat fighter, called the Clone Z-95. The Z-95 shares a striking basic resemblance to the X-Wing; Given that the X-Wing is the direct improvement to the venerable design.
After the Clone Wars, the Z-95 continued to receive upgrades, the most popular being the AF4 variant, which in addition to it's KX-5 laser cannons, included 2 sets of MG5 Concussion Missile launchers, one on each wing. It was an extremely potent and not to mention, cheap, fighter, picked up by every system defense force, criminal organization, and even the Rebel Alliance. The Rebel Alliance relied heavily on the Z-95, and was to a large degree the unofficial main fighter, until it was able to get it's hands on T-65 X-Wing Starfighters, which more or less replaced the Z-95 in combat duties, although it was still used extensively for patrols and in more isolated rebel units that could not acquire X-Wings.
The popularity of the Z-95 really didn't ever end. Z-95s are still a common sight, even some 60-70 years after the battle of Yavin, even up to and past the Yuuzan-Vong war. Parts flood the market, Z-95s sell for cheaper and cheaper, and in the hands of a good pilot, it can still pack a punch. System Defense groups can't afford anything better, but given that most won't engage in serious battle, a Z-95 is all they really need.
A service life extension program done by the Rebel Alliance, the Z-95 AF4H, also known as the Z-95 Heavy, or the Heavy-95, swapped the 4 2a ion fission engines with 4 4L4 fusial thrust engines designed for the X-Wing, hull and airframe re-enforcement, a Class 1 hyper drive and a concealed Astromech slot. All the systems were stripped down and built from the ground-up using more advanced and modern equipment.
This vastly increased it's effectiveness and thrust it back into it's slot as a primary attack fighter, though more in a relationship between it and the X-Wing similar to that of the F-16 and the F-15.
All told, it increased the speed to 100 MGLTs and 3,700 Gs acceleration, at 1,500 Km/H in atmosphere. It also gave hyperspace jump capability, with the astromech not only used to store jump coordinates, but also to conduct repairs.