The Sun King, King Louis XIV who ruled France from the 17th into the 18th century, adopted the Sun insignia to evoke how his position as the King of France was truly ordained as God’s representative in life.
In the iconography of ancient Egypt, the solar crown was taken as a disc framed by the horns of a ram or cow. It was worn by deities such as Horus in his solar or hawk-headed form, Hathor, and Isis, and was also worn by some pharaohs.
In Ptolemaic Egypt, the solar crown could also be a radiate diadem, modelled after the type worn by Alexander the Great (as identified with the Sun god Helios) in art from the mid-2nd century BC onward. It was perhaps influenced by contact with the Shunga Empire, and a Greco-Bactrian example was depicted at the great stupa of Bharhut. The first ruler of Egypt to wear this version of a solar crown was Ptolemy III Euergetes (246–222 BC).
In the Roman Empire, the solar crown was worn by Roman emperors in association with the cult of Sol Invictus, influenced also by radiant depictions of Alexander. The solar crown worn by Constantine, the first emperor to convert to Christianity, was reinterpreted as representing the "Holy Nails".
Above Left: Probus / Sol Invictus on Coin, Credit - https://en.wikipedia.org/wiki/Radiant_crown
Above Right: Ptolemy III on Coin, Credit - https://en.wikipedia.org/wiki/Radiant_crown
Below Left: Egyptian Aegis, Credit - https://en.wikipedia.org/wiki/Radiant_crown#/media/File:Aegis_with_incrusted_eyes_N3960_mp3h8698.jpg
Below Right: Louis XIV the Sun King, Credit - https://www.pinterest.ph/pin/308778118172325837/?lp=true