Karl Theodor Sapper (1866–1945) was a German traveller, explorer, antiquarian and linguist, who is known for his research into the natural history, cultures and languages of Central America around the turn of the 20th century.

Sapper spent over twelve years (1888–95) traveling through much of Central America, and in the process published a number of scientific works on aspects from vulcanology to Mesoamerican languages to descriptions and maps of Maya archaeological sites.

Sapper's contributions to the study of Mesoamerican languages include his initial proposal, made in a 1912 paper, which surmised that the highland regions of Chiapas and Guatemala was the location from which the Mayan languages and the Maya peoples later diversified. The assessment of a number of modern linguists places the likely home of the Proto-Mayan language as being centered around the Cuchumatanes highlands of Guatemala, with a subsequent early occupancy of the Chiapas highlands proper.

A sapper, also called pioneer or combat engineer, is a combatant or soldier who performs a variety of military engineering duties such as bridge-building, laying or clearing minefields, demolitions, field defences and general construction, as well as road and airfield construction and repair. They are also trained to serve as infantry personnel in defensive and offensive operations. A sapper's tasks are devoted to tasks involving facilitating movement of allied forces and impeding those of enemies.

The term "sapper" is used in the British Army, Polish Army, Commonwealth nations and U.S. military.

A sapper, in the sense first used by the Assyrian Army in the early 7th Century BC^{[citation needed]}, was one who excavated trenches under defensive fire to advance a besieging army's position in relation to the works of an attacked fortification, which was referred to as sapping the enemy fortifications.

Saps were excavated by brigades of trained sappers or instructed troops. When an army was defending a fortress with cannon, they had an obvious height and therefore range advantage over the attacker's guns. The attacking army's artillery had to be brought forward, under fire, so as to facilitate effective counter-battery fire.