Meaghan

I live in Ireland and nothing about any form of Megan is Irish. It was originally a pet form of Margaret in Welsh. If you want to have some form of Irish name related to Megan, then you use Mairéad, the Irish form of Margaret. Americans especially are so adamant that the name Meaghan/Maeghan/anything with a GH in it is Irish when it's just not.

Okay, any form of the name, whether it be Megan, Meghan, or Meaghan, is NOT Irish. This is NOT an Irish name, at all. So don't try and convince yourself that it is. Because there is absolutely no Gaelic connection with this name. It's Welsh. Get over it.

You're wrong too. The origin is not Irish or Welsh, even though they may use it (making it theirs). The actual origin is GREEK.

Two users said that the name Megan (the original spelling from which this variant derives) is Greek. This is blatantly false. Margaret, the name Megan is derived from, is a Greek name, but the Greek form of Margaret is Μαργαριτα. Μεγαν makes zero sense in Greek as a girl's name.