After centuries of lagging behind other apostle names Peter and Paul, Mark suddenly caught on in the early 1950s, reaching Number 6 by 1960. It was in the Top 10 from 1955 to 1970. At this point, it's Number 195 in the Social Security database and 263 on Nameberry.
Mark Twain was, of course, the pen name taken by Samuel Clemens. Prominent current bearers include actor Mark Ruffalo, Mark Wahlberg (the onetime Marky Mark) and Facebook founder Mark Zuckerberg.