The Propagator is a boss in Final Fantasy VIII. They come in four colors on the Ragnarok: purple, red, green, and orange, and must be defeated in pairs. They will respawn if the player does not kill them in pairs. The Propagator likes to use Silence and Blind, but these work well against them too.
One of the Propagators can, if Leviathan is boosted high enough, be pushed backwards off a platform and be killed instantly.
It is not entirely necessary to clear Ragnarok of the Propagators in their correct pairings. Continually challenging the Propagators randomly will, after a certain number of kills, cause all Propagators onboard Ragnarok to cease respawning.