Apollo
The only planet whose name in English is not derived from Greek or Roman mythology is Earth.
All the planets names are from Roman mythology, not Greek.
Earth
Answer: Janus's Name in Greek mythology is Ianus. Many of the Roman gods were actually Greek before the Romans conquered them and incorporated their gods into the Roman religion.
Basically, the only difference was their names, except for Apollo, who had the same name in both Greek and Roman mythology.
ours. Earth.
In Roman mythology he was known as Mars
Out of the old nine, I would say Earth.
Earth (Gaia) is the only planet whose English name does not derive from Greek/Roman mythology. The name derives from Old English and Germanic. There are, of course, many other names for our planet in other languages.
Achilles was a hero from Greek mythology that lead to the victory at the Trojan War, he is the greatest warrior and hero from Homer's epic poem, 'The Iliad'. He is also referred in the Roman mythology, under the same name, since he was a mortal, not a God, Romans only changed the names of the Greek Gods.
Poseidon. He was named Neptune in Roman mythology. He is not only god of the sea, but god of earthquakes, horses, and hail.
If you mean to ask, "Are there root words from Greek or Roman anicent mythology?" then, yes. A massive amount of names, phrases, and English grammatical terms are derived from Greek or Roman mythology. For example, the name Sophia or Phillip or any other name with the "PH" in it is Greek. Or the phrase, "my Achilles Heel" actually orginated from the Trojan War hero, Achilles. Legend has it that Achilles was dipped into the River Styx by his heel to become immortal, but since his heel was left undipped it was the only immortal part of him. His only weakness. Or say the word apostrophe. We see the "PH" combo so it is, in fact, derived from Greek.