Eternatus' extraterrestrial nature and
dragon-like appearance may be inspired by
Uther Pendragon,
King Arthur's father, who acquired his
epithet and started using dragons on his
standards after witnessing a dragon-shaped comet.
Its overall body shape resembles the skeletal remains of a dragon, with the ribcage shaped like a cannon. Its Eternamax form may be based on the biblical
Seven Headed Dragon that, in the
Book of Revelation, throws one-third of all stars down to the Earth and is ultimately is banished to Earth with the
Nephilim, the Hebrew giants, an event that ultimately leads to the
end of time. This account may also be the origin of the item
Wishing Star and the
Darkest Day.
Eternamax Eternatus may be inspired by
Ananta Shesha, the king of Nagas in Hindu mythology who is usually portrayed as a giant, coiled serpent with a thousand heads capable of spewing venom and fire, though some depictions simplify his appearance down to five heads. Shesha bears the deity
Vishnu on its coils, similar to how Eternamax Eternatus's core is mounted atop its coiled body.