Entity? Demon? Spirit? Who was or is he? How or by who’s power was this bieng controller?
Solomon is said to have employed a number of demons in building his temple, but the name you are probably seeking is Asmodeus.
The Testament of Solomon, pseudepigraphically attributed to Solomon but thought to have been written between 0 and 500 CE, is the first source you should go to here. The text names many of the demons who are said to have built the temple under Solomon's command. Asmodeus, who also appears in the Book of Tobit and the Ars Goetia, is described as preparing all the clay used in the building's construction, by trampling it down with his feet.