What's a common interjection for the reaction to something creepy and disgusting (like some insects or spooky places, etc.)?
For example,
A: - Look! There is a centipede on the table!
B: - (interjection)!
As the other answers have mentioned, eek (with long E as in "bleak") expresses fright, while yuck expresses disgust; I think ugh may also be suitable, depending on context: it can express both disgust and contempt.
Ew works in place of yuck or ugh, especially if the speaker is a child.
Eek!
That's what immediately comes to my mind.