  Certain debris disks have non-axisymmetric shapes in scattered light which
are unexplained. The appearance of a disk depends on how its constituent
Keplerian ellipses are arranged. The more the ellipses align apsidally, the
more non-axisymmetric the disk. Apsidal alignment is automatic for fragments
released from a catastrophic collision between solid bodies. We synthesize
scattered light images, and thermal emission images, of such giant impact
debris. Depending on the viewing geometry, and if and how the initial apsidal
alignment is perturbed, the remains of a giant impact can appear in scattered
light as a one-sided or two-sided "fork", a lopsided "needle", or a set of
"double wings". Double wings are difficult to reproduce in other scenarios
involving gravitational forcing or gas drag, which do not align orbits as well.
We compare our images with observations and offer a scorecard assessing whether
the scattered light asymmetries in HD 15115, HD 32297, HD 61005, HD 111520, HD
106906, beta Pic, and AU Mic are best explained by giant impacts, gravitational
perturbations, or sculpting by the interstellar medium.
