The Dater Glacier is a steep valley glacier in Antarctica, long and from wide, flowing northeast in a sinuous course from the eastern slopes of the Vinson Massif to Rutford Ice Stream which borders the eastern flank of the Sentinel Range, Ellsworth Mountains. At the lower end the Dater Glacier coalesces with the terminus of the Ellen Glacier, the two emerging from the Sentinel Range as one stream just north of the Flowers Hills.