V is for

Vixen

By Prang [Public domain], via Wikimedia Commons
Another scary Santa

and Dasher, Dancer, Prancer, Comet, Cupid, Donner, and Blitzen.

So we've already established that Santa used to arrive on a donkey before he upgraded to a fleet of magical reindeer and a sleigh. We also know that they are likely to be girl reindeer. And that they fly (or at the least float--remember the air trapped between fur and skin). But where did they get their names?

Much more like the Santa we are used to seeing.
Although the moon looks kinda scary in this one.

They first appeared in 1823 in the poem 'A Visit from St Nicholas' which later became '('Twas) The Night Before Christmas'. In the original version Donner and Blitzen were called Dunder and Blixem, which was Dutch for Thunder and Lightning. It appears that over the years these names have morphed into the ones we have now but nobody can say quite when (or why) that happened. One theory is that the names were changed to the German for thunder and lightning, which is donner and blitz, thereby becoming Donner and Blitzen. They were certainly named as such by the time the story of Rudolph came into being in 1939.