The Harry Potter franchise has a number of witches and wizards whose powers significantly surpass those of their immediate peers. Whether it be the reputation of Dumbledore as the only wizard Voldemort feared or the prowess of Gellert Grindelwald some seventy years previously, there are certain magic users who stand out from the crowd. One of the earliest examples of this is Merlin, a legendary figure in the wizarding community whose abilities in certain areas were surpassed only by his depth of knowledge of the craft. That is true to such an extent that he is the only character who can rightly say he would defeat Voldemort -- and do so quite easily.
Source：https://www.cbr.com/how-powerful-merlin-harry-potter/
