No, wait a minute -- that's not quite right. Perhaps it would be more accurate to say most people are familiar with some of Friedrich's famous creations, but are largely unaware of Friedrich himself.
For example, I imagine almost everyone has come across an image of this painting at some point . . .
I know I couldn't when I first saw it . . . and then saw it again . . . and again.
Friedrich was primarily a landscape painter. Even better, he was a Romantic landscape painter, which means his landscapes communicate a subjective and emotional response to the natural scenes he depicted. He was also fond of including human figures in his landscapes, but in a way that, according to Wikipedia, set a human presence in diminished perspective amid expansive landscapes, reducing figures to a scale that, according to the art historian Christopher John Murray, directs "the viewer's gaze towards their metaphysical dimension."
The Friedrich landscape that sparks the biggest subjective and emotional response in me is his The Evening Star -- for the simple reason that it so very much resembles the landscape I currently inhabit here in western Hungary, which makes the whole "metaphysical dimension" aspect of the painting easily accessible and comprehensible.