A fantastic illustration from Derek Chatwood (The Searcher on Flickr
) showing ol' McGrumpy as the Unoriginal Maverick
that he is.
But until the NY Times told us how the term originated
I didn't know that it relates to a family in Texas. Back in the day, they had a cattle ranch, and didn't bother to "brand" the cattle as other ranchers did, so any unmarked livestock were assumed to be "Maverick's".
The sad part of the story is that the family has had a long history of progressive political views. Predictably, they are none too happy over his usurpation of the term to "brand" his increasingly desperate and negative campaign.