Olympian vs Twelve Olympians

Olympian and Twelve Olympians both are nouns.

Word	Noun	Adjective	Verb	Adverb
Olympian	Yes	Yes	No	No
Twelve Olympians	Yes	No	No	No

As nouns, Olympian and Twelve Olympians are synonyms defined as:

Olympian and Twelve Olympians: a classical Greek god after the overthrow of the Titans

Other synonyms of Olympian include Olympic god.

Olympian (noun)	Twelve Olympians (noun)
an athlete who participates in the Olympic games	a classical Greek god after the overthrow of the Titans
a classical Greek god after the overthrow of the Titans

Olympian (adjective)	Twelve Olympians (adjective)
of or pertaining to the greater gods of ancient Greece whose abode was Mount Olympus
of the region of Olympia in Greece or its inhabitants