In recent years several universities, government laboratories, and private industries have been developing specific process technologies, analytical modeling tools, and characterization methods for highly porous metals and alloys frequently collectively termed ``ultralightweight metals.'' The goal has been to achieve a family of metallic structures that are analogs to the organic cellular materials that exhibit high stiffness and a low specific weight. A number of different and distinct processes have evolved and are still largely not yet mature. To date, the imaging capabilities of X-ray computed tomography have not been generally employed to nondestructively examine the internal structure of the products formed by these various processes. This article briefly reviews the principles and terminology of X-ray computed tomography as it has evolved through successive generations and then presents several types of computed tomographic images of ultralightweight metallic specimens produced by different process technologies. The images for each specimen are preceded by a brief description of the process technology that created it.