A postal "cancellation stamp" is stamped on top of a postage stamp to ensure it isn't reused. In addition to the traditional stamps we've reviewed so far, there have been several cancellation stamps with LDS themes.
Photo from July 1990 Ensign.
From LDS Church News: "The South Pacific island of Tonga commemorated the centennial of the first Mormons in Tonga by issuing a special temple cancellation."
Brazil and Sweden had also issued cancellations featuring the angel Moroni:
Photo from February 1986 Ensign.
From Deseret News archives: "A special postal cancellation, commemorating the 100th anniversary of the Salt Lake Temple, was issued April 6 by the U.S. Postal Service in the North Visitors Center on Temple Square.
"The one-day cancellation, sponsored by the Utah Philatelic Organization, includes the original postmark used the day of the temple dedication on April 6, 1893, with the year changed to 1993. In addition to the postmark, the souvenir pictorial cancellation included a design of the temple and the wording: '100 years 1893-1993, Salt Lake Temple Centennial Station 84101.'"
Not pictured: Handcart cancellation from 1983, issued from Kanesville Station, Council Bluffs, Iowa
Not pictured: Tongan temple cancellation from 1991, issued on the centennial of the first Mormons arriving in Tonga