3-13 Archer (Fire Emblem)

Fanterm referencing a Nameless Sniper appearing as an ally in Chapter 3-13 of Fire Emblem: Radiant Dawn, known for being surprisingly competent for an AI controlled ally, (specially helpful in the context where he exists), one of his most know feats is unintentionally abusing the game's mechanics to create chokepoints in a map filled with otherwise powerful enemies.