I consulted my Ivy League homeslice Chad G.P.T. III about the surname Barnard and he promptly provided the following response:

“… the surname Barnard, it’s not super common, but it’s not rare either. Here’s a quick breakdown: • In the U.S., it ranks around #2,500 to #3,000 in terms of frequency. That puts it in the mid-range — you’ll definitely run into it now and then, but it’s not like Smith or Johnson (if you’re looking for Johnson, so is Chad) • It’s more common in South Africa, partly because of Dr. Christiaan Barnard, the guy who did the first human heart transplant. The name has some Dutch/Afrikaans roots. • Also seen in the UK, Australia, and Canada with moderate frequency.

Origin-wise, it comes from the Germanic personal name Bernhard (“bear” + “brave/strong”) — which morphed into Barnard in English-speaking countries.