is it donder or donner

Donder and Blitzen are the names of two of Santa's reindeer. They are often referenced in songs and stories about Christmas. In fact, in the 1800s, Donder and Blitzen were actually mentioned as two of the nine reindeer that pulled Santa's sleigh, along with Dasher, Dancer, Prancer, Vixen, Comet, Cupid, and Rudolph. So, to answer your question, Donder and Blitzen are the correct names of the two reindeer.