True Neutral
Fear of spiders is an inate defense response passed down by survivors of spider encounters. It is a behavior accessible to creatures of all alignments.
How funny would it be to have the BBEG & an arachniphobic paladin cluch eachother in fear of a wildshaped giant wolf-spider?
Post-clarification answer: unaligned
Most reference books have normalish spiders categorized as unaligned beasts. They don't qualify as intelligent enough to have morals & ethics.