Time pirates

Time pirates are rogue time travelers that disregard the consequences of changing history in process of time travel for the sake of profit. These time criminals were hunted down by Time Masters and bounty hunters in their employ, such as Chronos and the Pilgrim, and later, after the Oculus device and a great part of Time Masters' HQ in the Vanishing Point were destroyed, by rogue Time Master Rip Hunter's vigilante team: the Legends. Time pirates, as well as other time criminals, are often the source of historical aberrations.

Overview
Time pirates operate on time ships, a type of spaceship that is also able to travel through time. Unless created by themselves, the pirates use captured vessels of Time Masters in their illicit trade, and generally seek out new ships to capture. The pirates use futuristic weaponry that they also sell to buyers throughout time, including to those leaving in Medieval time period, causing potential aberrations.

History
Rip Hunter's team first encountered time pirates while trying to contact Acheron, a flagship of the Time Masters' Time Fleet, owned by Eve Baxter. Deciding to rescue Eve in exchange for getting an updated Time Masters' database that would help locate Vandal Savage's appearances throughout time, Rip Hunter and a part of his team boarded Acheron, only to get captured by Jon Valor and his gang of time pirates. Rip tried to negotiate their release, but Jon didn't buy his bluff and held Rip hostage, wanting to trade him and his team's lives in exchange for the Waverider. While Mick Rory temporarily sided with time pirates, the team managed to overpower them and take back both ships, acquiring the necessary database from Eve Baxter.

The team, now calling themselves the Legends, would further encounter time pirates in the future, after severely weakening the Time Masters organization, destroying their hold on timeline. Now choosing to protect the timeline from various time criminals themselves, the Legends started targeting historical aberrations, usually caused by time pirates. Preventing or negating the effects of aberrations, the Legends kept the timeline in (roughly) the same form. One such aberration would include a battle against blaster-wielding assassins in 17th century France, with their futuristic weaponry provided by the time pirates.