The name Megan is originally a Welsh pet form of Margaret. It has been mistaken as an Irish name in the USA and sometimes 'Irishized' with the spellings Meaghan, Meghan etc. The spelling Meghan has Australian author Colleen McCullough to blame, McCullough may have first coined that spelling for the protagonist her book The Thorn Birds. In fact, it is likely because of her fiercely Irish heroine Meghann, that the whole notion that Megan is an Irish name got started, or at least furthered it. For those who insist that Megan is Irish, and there are many militant pro-Megan Irish-Americans out there who have emailed me, There are the obscure Irish surnames, Meigan and Meegan. However, these names have usually been found as Meehan in this century. Meggin is another rare Irish surname, a variant of McGinn.
Outside of Wales, this name has been used only since the mid 20th century.
See Also: Meeghan, Meghan, Meghann, Magen, Margaret