You can't go a December without seeing someone posting (see below) the infamous David Bowie and Bing Crosby duo performance of "Little Drummer Boy/Peace on Earth" on Crosby's 1977 holiday special, Merrie Olde Christmas. Rarer is this second performance from that show, Bowie performing "Heroes" to a backing track. It is allegedly the first live performance of the vocals. Above is a revised edit of the video.
Trigger warning: Mime-moves ahead.