Megan is one of the most frequently appearing characters of the webcomic xkcd.
She initiated the building of the Sandcastle.
Seems to be a faster builder than Cueball, although with the consistency of the frame rate still unsure, we can not say for certain. She also is the principal designer, having started the first turret, the rampart and second turret, the waterside extension with the arch, and then the central tower of the initial sandcastle. She apparently was also responsible for the building of the second more elaborate sandcastle away from the shore.
She also appears to be rather clumsy and trips several times.