UPDATE: Mary Did You Know was written by Mark Lowry and Buddy Greene. I stand corrected; read the comments below.
Mary Did You Know was originally written by Mark Lowry in 1984. Lowry is best know for being a comedian, and practically made a career out of making fun of Bill Gather. Michael English was the first artist to release it on his debut album in 1992.
Here is Mary Did You Know performed by Mark Lowry, with scenes from the Jesus film.
*The video description spells his name incorrectly; Lowry not Lowery is correct.
If you prefer Michael English:
Kenny Rogers and Wynonna Judd:
And finally Kutless:
There are many covers of this song, from Kathy Mattea to Donny Osmond. You can knock yourself out on YouTube. I think the mere fact that every man and his brother has recorded a version of this says a great deal about its popularity.