William Niven (2 October 1850 – 2 June 1937) was a mineralogist and archeologist noted for his discovery of the minerals yttrialite, thorogummite, aguilarite and nivenite (named after him), as well as a set of controversial tablets.

Niven's first major contribution to mineralogy occurred in 1889 while he was on an expedition to Llano County, Texas, on behalf of Thomas Edison.

In 1921, Niven discovered the first of over 100 andesite tablets on a dig in San Miguel Amantla, Azcapotzalco, which was an important city-state conquered by Aztec Triple Alliance in 1431.

After viewing rubbings of Niven's tablets Churchward strongly believed that there were a group of people that escaped destruction and migrated to other parts of the world spreading their culture and belief system.

Historian Ronald H. Fritze has noted that archaeologists have dismissed Churchward's pseudohistorical ideas and Niven's tablets were a "crude although voluminous hoax".

Niven is the basis for the character William Givens in Katherine Anne Porter's short story Maria Concepcion.