There are two reindeer in Santa's team that begin with the letter 'D'. They are Dasher and Dancer. These two reindeer are known for their speed and agility, making them perfect for leading the sleigh through snowy landscapes and challenging terrains. Dasher is known for his stamina and endurance, while Dancer is known for his grace and elegance. Together, they make a dynamic duo that helps ensure Santa's Christmas Eve journey is a success every year.