Did William Barclay "Bat" Masterson get his nickname from his real birth name, Bartholemew?

Yes William Barclay "Bat" Masterson got his name from his real birth name which was Bartholemew Masterson, but he later used the name William Barclay Masterson.

https://en.wikipedia.org/wiki/Bat_Masterson#Name_and_birth

Apparently not. Masterson dressed in expensive Eastern clothing and preferring to use his cane rather than a gun to get himself out of trouble (also the case with the real Masterson), hence the nickname "Bat."


https://en.wikipedia.org/wiki/Bat_Masterson_(TV_series)

I'd sure have to wonder about anyone like Masterson beginning to use the nickname Bat well after he'd already earned a rep as an old west icon. The boy was using it a fair bit before his gunfight injury--as a very young man, the site says--which would make perfect sense to me for anybody birth named Bartholomew and schmoozing with Army scouts, buffalo hunters, lawmen, etc. Frankly, because of the way legends such as his are concocted, the real story will probably never be known.
Odds are also pretty good that it was Hollywood's influence upon Gene Barry's portrayal of Masterson and his penchant for using that trusty cane. Funny thing is, if Bat indeed needed it for walking support, I don't ever recall seeing Mr. Barry limping.

http://www.historynet.com/bat-masterson.htm

Another version:

It was as a hunter he won his name of 'Bat', which descended to him, as it were, from Baptiste Brown, or 'Old Bat', whose fame as a mighty nimrod was flung all across, from the Missouri River to the Spanish Peaks, and filled with admiration that generation of plainsmen which immediately preceded Masterson upon the Western stage.

http://www.homeofstone.org/index.php?page=w.-b.-bat-masterson