The most common and most likely answer to this crossword clue is the 7 letter word CYCLOPS
I've seen this crossword clue in The Daily Telegraph
C
Y
C
L
O
P
S
More clues leading to the result CYCLOPS
- Giant penny-farthing with no rear wheel? “Penny Singular”
- One with ocular singularity has operations on endless rotation
- Mythical creature in loch captured by heartless city police
- One who sets young Conservative loutish leaders breaking the law
- Giant bikes require work to replace a bearing
- Giant encyclopedias omitting various parts of Aeneid
- Giant bike missing rear end works
- Singular-looking giant?
- Giant – as opposed to giiant, you might say?
- Sound from hooves on extremely clumsy monster
Buddy explains!

The straight part
We know that "Fantastic character" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fantastic character = cyclops.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CYCLOPS mean?
CYCLOPS noun- A one-eyed giant from Greek and Roman mythology.
- A one-eyed creature of any species.
- A person with only one working eye.
- Any copepod in the genus Cyclops