Princess Fish

A Hallow catch, so it is off the table until the world turns and you have Hallowed ground with water in it. Depth does not change whether one bites, which is the useful part: fish an underground Hallow pool instead of a surface one, because it is far easier to wall off a small cave and stand still safely than it is to hold a spot out in the open with Hardmode enemies wandering past.

The two things you can make with it pull in opposite directions. The Seafood Dinner is a real food buff and the reason to bank a stack. The Love Potion is a party trick you will craft once and never think about again.