"The Chipmunk Song (Christmas Don't Be Late)" is a song written by Ross Bagdasarian, Sr. (a.k.a. David Seville) in 1958. Although it was written and sung by Bagdasarian (in the form of a chipmunk voice), the singing credits are given to The Chipmunks, a fictional singing group consisting of three chipmunks by the names of Alvin, Simon, and Theodore.

The Chipmunk Song was very successful, reaching #1 on the Billboard Hot 100 Pop Singles chart, becoming The Chipmunks' first (and only), as well as David Seville's second and final, #1 single.
~Source: Wikipedia