creep has 14 distinct synonyms spread across 5 of its 8 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
someone unpleasantly strange or eccentric
a slow longitudinal movement or deformation
a pen that is fenced so that young animals can enter but adults cannot
a slow mode of locomotion on hands and knees or dragging the body
“a crawl was all that the injured man could manage”
to go stealthily or furtively
“..stead of sneaking around spying on the neighbor's house”
Synonyms, antonyms and the broader and narrower relations for creep come from Princeton University’s WordNet. Full sources and licences.
grow or spread, often in such a way as to cover (a surface)
“ivy crept over the walls of the university buildings”