Erik Wilhelm "Loppan" Adlerz (July 23, 1892 – september 8, 1975) was a Swedish diver who competed in the 1908 Summer Olympics, in the 1912 Summer Olympics, in the 1920 Summer Olympics, and in the 1924 Summer Olympics.
At his first Olympic Summer Games in 1908 he was eliminated in the first round in the 10 metre platform event.
His last Olympic appearance was 1924 at the Olympic Summer Games in Paris. In the 10 metre platform event he finished fourth, but in the plain high diving he was eliminated in the first round. He is buried in the Skogskyrkogården (The Woodland Cemetery) in Stockholm.