We prove a multivariate strengthening of Brenti's result that every root of the Eulerian polynomial of type B is real. Our proof combines a refinement of the descent statistic for signed permutations with the notion of real stability-a generalization of realrootedness to polynomials in multiple variables. The key is that our refined multivariate Eulerian polynomials satisfy a recurrence given by a stability-preserving linear operator.Our results extend naturally to colored permutations, and we also give stable generalizations of recent real-rootedness results due to Dilks, Petersen, and Stembridge on affine Eulerian polynomials of types A and C. Finally, although we are not able to settle Brenti's real-rootedness conjecture for Eulerian polynomials of type D, nor prove a companion conjecture of Dilks, Petersen, and Stembridge for affine Eulerian polynomials of types B and D, we indicate some methods of attack and pose some related open problems. Conjecture 1.1 (Conjecture 5.2 in [9]). For every finite Coxeter group W, the descent generating polynomial W(x) has only real roots. Dilks, Petersen, and Stembridge later extended the definition of Eulerian polynomials to include affine descents, and proposed the following companion to Brenti's conjecture. Conjecture 1.2 (Conjecture 4.1 in [12]). For every finite Weyl group W, the affine descent generating polynomial W(x) has only real roots.Again, this was not completely proved-A n (x) and C n (x) were shown to have only real roots, the exceptional cases were verified, but the real-rootedness of the affine Eulerian polynomials of types B and D remains an open problem.