The Eight Units are items in I Wanna Be The Guy, that are neccesary to collect to become The Guy. The
Legend of Zelda-style introduction to the game mentions the units, a direct parody of the Eight Units of the triforce from Zelda, which The Kid must collect by defeating the bosses of the game.

These units appear as red circles which resemble the Magic Crystals from Castlevania and appear after The Kid beats a boss. After collecting the unit, a victory tune, one fitting the boss just beaten, will play. It is interesting to note that, although there are eight bosses, and eight units mentioned in the introduction, the red units will only appear after the defeat of the first six bosses; not after the defeat of the Devil Dragon or The Father.