But being "illegal in the first place" almost always hinges on consent, at least in the case of crimes that have victims. (Victimless crimes obviously cannot hinge on consent because there's no one to consent.) I think you'll find it very challenging to come up with an example of an action that is a crime with a victim that doesn't involve lack of consent as an essential element. The only example I can think of offhand is statutory rape, and in that case it's only independent of consent because the victim is explicitly barred by law from giving consent.
Here in the UK I can add: assisted suicide, many sexual activities particularly on camera (even between very enthusiastic participants), driving in a vehicle on the public highway without a seatbelt, working for under the minimum wage, corporal punishment and polygamy.