Manservant

Manservants (男性使用人) are a group of ten butlers that maintain the upkeep of the 9th and 10th Floors of the Great Tomb of Nazarick.

Background
The Manservants, like the Homunculus Maids, are responsible for the various minor miscellaneous jobs, especially the cleaning on the 9th and 10th Floors of Nazarick. They are subordinates of Eclair Ecleir Eicler.

The Dark Warrior Arc
One Manservant was standing attentively at Eclair's side when he was speaking to Demiurge. The butler monster then carried his superior to his next destination.

The Lizard Man Heroes Arc
Eclair had a Manservant carry him to the bar on the 10th Floor. Sous-chef served the penguin a drink, and while he offered one to the butler, but he declined.

The Two Leaders Arc
One Manservant was manning a buffet table in the staff canteen, serving food to the Homunculus Maids. Another of its colleagues had come into the canteen following CZ2128 Delta as she carried the assistant butler in her arms.

Ainz’s Ambition Arc
The Manservants were assembled on the 9th Floor in preparation for Ainz's three-day vacation alongside their superior Eclair and the rest of the Nazarick work staff.

Strength
They are domestic workers and so far have displayed no combat abilities. They also seem to possess some cooking skills as one was able to make an omelet.

Trivia

 * All the manservants wear full-face battle masks, like faceless mooks, and only communicated in strange noises.
 * They are most likely a reference to Shocker, a recurring enemy type from the Kamen Rider series.
 * The Manservants are dressed entirely in black with white gloves.