Starkillers were Apokoliptian battleships.
Steppenwolf attacked New Genesis, but was ambushed by Orion's forces. Only two Starkillers managed to escape at first, but one of them was destroyed soon after. Alone and defeated, Steppenwolf contacted Darkseid, who offered no help. Orion destroyed the other Starkiller as well, and boomed it into Darkseid's palace.