R.O.B. Sentry

The R.O.B. Sentries are robots loyal to the Ancient Minister (the playable R.O.B.). The R.O.B. Sentry uses a two-armed punch attack. Two R.O.B. Sentries are sacrificed at a time to detonate a Subspace Bomb. R.O.B. Blasters and R.O.B. Launchers are more advanced varieties of R.O.B. Sentries.

On a side note, R.O.B. Sentries are one of three Subspace Army enemies to appear in at least one cutscene.