Watcher

A  is an enemy featured in Skyward Sword. They, along with the Guardians, protect and patrol the Silent Realm. However, unlike the Guardians, the sentries are not affected by the Tears of Light and thus will not be stunned by its power.

The Siren Sentries shine a light through the realm. If Link passes through this light, the Siren Sentry will emit a loud sound that will awaken the Guardians, canceling the effects of the Tears of Light.