“I’m just enraged that McCain calls himself a maverick,” said Terrellita Maverick, 82, a San Antonio native who proudly carries the name of a family that has been known for its progressive politics since the 1600s, when an early ancestor in Boston got into trouble with the law over his agitation for the rights of indentured servants.

I enjoyed this history of the Maverick family, many of whom seem to have made their mark on American culture. However, I'm not sure the NYT account is entirely accurate.

Wikipedia has Samuel Maverick as one of the first Slave holders in Massachussets. Wikipedia seems to largely rely on this source which suggests that he got in trouble with the government for bringing slavery to the colony, and not because he was agitating for anyone's rights.

If not the earliest, Maverick was one of the earliest slaveholders in Massachusetts, having purchased one or more slaves of Capt. William Pierce, who brought some from Tortugas in 1638. Slavery was always repugnant to the feelings of our Puritan fathers, and from this fact, and the Episcopacy of Maverick, there was gradually engendered an ill-feeling between him and the government, which began to show itself as early as March, 1635, when the Court ordered Maverick to leave Noddle's Island by the following December, and take up his abode in Boston, and, in the "meantyme" not give "entertainment to any strangers for a longer tyme than one night without leave from some Assistant, and all this to be done under the penalty of £100."

The Nation - Who You Callin’ a Maverick? - NYTimes.com