Which term can refer to a person who is overly eager to please?

The term that refers to a person who is overly eager to please is "toady." This word specifically denotes someone who flatters or ingratiates themselves to others, often for personal gain or to curry favor. A toady may go out of their way to please someone in a position of power or authority, sometimes to the point of insincerity. It reflects a mindset focused on subservience and excessive politeness, which fits the description of having an overly eager desire to please.

In contrast, the other options do not carry this meaning. A servant provides assistance or performs tasks but does not inherently suggest an eagerness to please beyond their duties. Comrade typically refers to a companion or colleague, especially in a political context, without any connotations of obsequiousness. Monitor signifies someone who observes or regulates, lacking the idea of pleasing others. Therefore, "toady" is the most fitting choice for someone characterized by their excessive eagerness to please.