(The reimagined series; Caprica and Blood & Chrome)
The Heavy Raiders were constructed in the years leading up to the Fall of the Twelve Colonies, and saw heavy deployment during that conflict, with their initial task being to ferry a massive Centurion army to the surfaces of every inhabited world to exterminate survivors of the nuclear bombings conducted by the Basestars. Following the extermination, the Heavy Raiders continued to see use in transporting supplies to be used in construction projects while the planets were under occupation. When the occupation ended nearly a year later, these Raiders presumably evacuated remaining Cylons.
Heavy Raiders saw use by a Rebel Basestar during the Battle of the Hub, and fought alongside Vipers. Due to severe limitations brought on the Cylon rebel faction, the Heavy Raiders were crewed by Humanoid Cylon pilots instead of Centurions.
The Heavy Raider is near-analogous to the modern Raptor models used by the Colonial Fleet. Both are designed to ferry troops and supplies from ship-to-ship or ship-to-surface and are capable of faster-than-light jumps. However, unlike the Raptor, the Heavy Raider also serves as a gunship if necessary.