As I understand it, in the original Irish there's no apostophe and the apostrophe was added by English speakers because of a mistaken idea that it's short for "of the", as in "five o'clock". Of course, a lot of names are also spelt differently in Irish:

O'Rourke = Ó Ruairc

O'Reilly = Ó Raghallaigh

O'Donovan = Ó Donnabháin

So you could get rid of the apostrophe and at the same time really spice your name up, perhaps.