Just search: Python. Also for ellipsoids, you can use vtkTransform on a sphere e.g. something like this:
trans = vtkTransform()
trans.Scale(1, 0.5, 0.333)
sphere = vtkSphere()
sphere.SetRadius(1)
sphere.SetTransform(trans)
The example above does have a sphere as a source, so you could possibly transform it into an ellipsoid.