Single crystals of a one-component plasma were observed by optical Bragg diffraction, The plasmas contained 10(5) to 10(6) single-positive beryllium-9 ions (Be-9(+)) at particle densities of 10(8) to 10(9) per cubic centimeter. In approximately spherical plasmas, single body-centered cubic (bcc) crystals or, in some cases, two or more bce crystals having fixed orientations with respect to each other were observed. In some oblate plasmas, a mixture of bce and face-centered cubic ordering was seen. Knowledge of the properties of one-component plasma crystals is required for models of white dwarfs and neutron stars, which are believed to contain matter in that form.