The standard assumption is Linear Algebra, a complete Calculus sequence (including multivarate), and Differential Equations.
From what I have actually seen in my upper division course load taking courses on the following math subjects are also useful:
Differential Geometry, Tensor Anaylisis, Complex Anaylisis/boundary Value Problems, Calculus of Variations, a course on Waves/Oscillations from a math department (if offered), and an applied group theory course.
A few stats courses, like ones designed for science and engineering majors and/or some numerical methods courses (my math department splits them between math and stats pretty evenly, so I don't know where one would like to place it).
However, as I said before the first list is likely the only required mathematics course work in physics, the rest are just good subjects to pick up on the way.