I am often delighted by the English names that some Koreans choose to adopt for themselves in an effort to simplify life for us waegookin (foreigners). Singers and actors are always popular sources for Koreans that choose their own English names. It should be noted that around half of my Korean friends take English names - the rest have figured out that some non-native speakers don't butcher Korean pronunciation too much.
My favourites that I've come across in my time in Seoul are Al Pachino Cho (spelling mistake courtesy of his business card) and Harrison Lee (who makes no bones about being a huge fan of the actor). This phenomenon isn't unique to Korea but is a fun little side-effect of being a stranger in a stranger land.
For the record, my Korean name is 매튜.