Fallout 4: Giant Creatures Guide, How to Find and Kill [PS4 - Xbox One - PC]
Even those ugly of the giant creatures of Fallout 4 advise you to consult the complete guide and tricks card of Fallout 4 where you will find many other useful guides on this game.
Guide to find and kill giant creatures
In Fallout 4, the only two creatures that are classified as "giants" are the Behemoths and Regine Mirelurk. If you manage to kill 5 of them you will unlock the Trophy / Objective "... the more noise they make when they fall", but remember that in order to be counted as your kill, you will have to deliver the killing blow.
A couple of giant creatures are found in some story missions, but considering that you will be together with other characters it is likely that someone will steal the Kill from you. For this reason I recommend watching the video below showing some places on the map where giant creatures are found, places that you can visit at any time:
Obviously you will have to show up well equipped, essential the Fat Man or at least a rocket launcher, as well as the power armor (if you are not well protected these beasts will be able to kill you with a single shot ...). Remember that after killing them they will no longer appear and that each of them will always drop rare loot.