HTC One has been the Taiwanese company's flagship line for some time, even dating back before the M7, M8 and soon-to-be M9 phones were launched. We actually can trace the HTC Origins back to a trio of phones — the HTC One X, One S and One V in 2012. But that early branding understandably created some confusion, and things have been pared down a bit.
So today when we talk about the HTC One line, we're really talking about these devices. Be sure to hit the links to learn more about each: