Franz Xaver Messerschmidt (February 6, 1736 – August 19, 1783) was a German-Austrian sculptor most famous for his "character heads", a collection of busts with faces contorted in extreme facial expressions.

Here, in the building's salon in 1760-63 he made his first known works of art, the bronze busts of the imperial couple and reliefs representing the heir of the crown and his wife.

To this trend belong two other, larger than lifesize tin statues representing the imperial couple, commissioned by Maria Theresa of Austria and executed between 1764 and 1766.

One of these early, severe heads from the years 1769–70, influenced by Roman republican portraits, represents the well-known doctor Franz Anton Mesmer.

In a letter to the Empress, Count Kaunitz praised Messerschmidt's abilities, but suggested that the nature of his illness (referred to as a "confusion in the head") would make such an appointment detrimental to the institution.

Nicolai's account of the meeting is a valuable resource, as it is the only contemporary document that details Messerschmidt's reasoning behind the execution of his character heads.

As a result, Messerschmidt claimed that his character heads had aroused the anger of "the Spirit of Proportion", an ancient being who safeguarded this knowledge.