der Wächter
guard
A person whose job is to guard something or someone and protect them from danger, theft, or unauthorized entry.
Ein Wächter patrouilliert nachts um das Museumsgebäude.
A guard patrols around the museum building at night.

guard
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guard
A person whose job is to guard something or someone and protect them from danger, theft, or unauthorized entry.
Ein Wächter patrouilliert nachts um das Museumsgebäude.
A guard patrols around the museum building at night.

The noun 'Wächter' (guard) is derived directly from the verb 'wachen' (to watch/keep guard). The ending '-er' indicates the person who performs the action of keeping watch.
Die Aufgabe des Wächters ist es, die ganze Nacht zu wachen.
The guard's job is to keep watch all night.
When you want to express what a guard is watching over, the preposition 'über' with the accusative is often used. This construction comes from the verb 'wachen über' (to watch over).
Er ist der Wächter über die königlichen Juwelen.
He is the guardian of the royal jewels.
In its concrete meaning, 'Wächter' (guard) is often combined with the place or time of the watch, for example as 'Nachtwächter' (night watchman), 'Museumswächter' (museum guard), or 'Torwächter' (gatekeeper).
Der Nachtwächter macht jede Stunde seine Runde durch die Altstadt.
The night watchman makes his rounds through the old town every hour.
You can recognize the figurative meaning by the fact that the 'Wächter' (guardian) watches over something abstract. Typical formulations are 'Wächter der Verfassung' (guardian of the constitution), 'Wächter der Moral' (guardian of morality), or 'Wächter über die Tradition' (guardian of tradition).
Die Presse wird oft als Wächter der Demokratie bezeichnet.
The press is often described as a guardian of democracy.
guard / station
'die Wache' and 'der Wächter' both have to do with guarding and protecting. 'der Wächter' is an individual person who watches over something. 'die Wache' can mean one person or a whole group, but also the duty itself, meaning the time during which someone keeps watch. That is why people say, for example, 'Wache halten' (to stand guard). Learners may confuse the words because in both cases someone is protecting something. The important point is: 'Wächter' mainly refers to the person, while 'Wache' often refers to the task, the duty, or a group.

Der Wächter schließt abends das Tor zum Gelände.
The guard locks the gate to the grounds in the evening.
Der Soldat hat in der Nacht Wache gehalten.
The soldier stood guard during the night.