The R.O.B. Sentry (ロボットアタッカー, Robot Attacker in Japan) is a member of the R.O.B. Squad and an enemy in the Subspace Emissary mode, encountered only on the Isle of the Ancients. It has a similar appearance to the hidden character, R.O.B.. The R.O.B. Sentry replaces Primids on the floating island, attacking with melee moves, which is limited to a simple arm swing, dealing around 23% with strong knockback and fairly long duration. Also, they too have variations that attack in different manners, as Primids do. According to the trophy description for R.O.B. Blasters, R.O.B. Sentries are equipped with beam firing capabilities, although they choose to participate in hand-to-hand combat.