We establish several nonuniqueness results for the problem of finding complete conformal metrics with constant (fourth-order) Q-curvature on compact and noncompact manifolds of dimension ≥ 5. Infinitely many branches of metrics with constant Q-curvature, but without constant scalar curvature, are found to bifurcate from Berger metrics on spheres and complex projective spaces. These provide examples of nonisometric metrics with the same constant negative Q-curvature in a conformal class with negative Yamabe invariant, echoing the absence of a Maximum Principle. We also discover infinitely many complete metrics with constant Q-curvature conformal to S m × R d , m ≥ 4, d ≥ 1, and S m × H d , 2 ≤ d ≤ m − 3; which give infinitely many solutions to the singular constant Q-curvature problem on round spheres S n blowing up along a round subsphere S k , for all 0 ≤ k < (n − 4)/2.