Saying a cow is famous sounds a little silly. However, when we consider that bovids like the Aurochs made such an impression on humans that they appeared in their cave art and have shown up in other forms like the videos, books, and even a toy or two like that below, it is difficult to say that Aurochs are not indeed famous.
Fame goes way beyond simply being popular. It is true that the Aurochs is a popular animal, so popular in fact that the great wild ox is being re-introduced to the wild. The active breeding program is still ongoing and rather than continuing to laud the many popular outlets I think we should end this week on a Tedx talk on "DeExtinction" about the precarious position of the potentially extinct giant ox: