The Impactors are a trio of alien warriors working for the Warp Monarch and the antagonists of episodes 13 to 24 in Chouseishin Gransazer.
The first two Impactors to arrive on Earth were Lucia and Radia. Radia initially took an interest in the Gransazers, despite believing them to not be strong enough to fight him, and soon developed a rivalry with Gorbion of the Water Tribe. Radia was later killed by the Water Tribe's Leviathan.
Radia's death prompted Lucia to swear vengeance against the Gransazers. However, Logia arrived and ordered Lucia not fight them just yet. Lucia disregarded these orders, and attempted to use the Accelerator to enlarge herself so she could destroy the Gransazers. The Gransazers manage to triumph over her, however, and Lucia dies as a side-affect of the Accelerator's powers, leaving Logia as the sole Impactor on Earth.