The Olmec colossal heads consist of at least seventeen monumental stone representations of human heads sculpted from large basalt boulders. The heads date from at least before 900 BC and are a distinctive feature of the Olmec civilization of ancient Mesoamerica. All portray mature men with fleshy cheeks, flat noses, and slightly crossed eyes; their physical characteristics correspond to a type that is still common among the inhabitants of Tabasco and Veracruz. The backs of the monuments often are flat. The boulders were brought from the Sierra de los Tuxtlas mountains of Veracruz. Given that the extremely large slabs of stone used in their production were transported over large distances, requiring a great deal of human effort and resources, it is thought that the monuments represent portraits of powerful individual Olmec rulers. Each of the known examples has a distinctive headdress. The heads were variously arranged in lines or groups at major Olmec centres, but the method and logistics used to transport the stone to these sites remain unclear.
The discovery of a colossal head at Tres Zapotes in the nineteenth century spurred the first archaeological investigations of Olmec culture by Matthew Stirling in 1938. Seventeen confirmed examples are known from four sites within the Olmec heartland on the Gulf Coast of Mexico. Most colossal heads were sculpted from spherical boulders but two from San Lorenzo Tenochtitlán were re-carved from massive stone thrones. An additional monument, at Takalik Abaj in Guatemala, is a throne that may have been carved from a colossal head. This is the only known example from outside the Olmec heartland.
Dating the monuments remains difficult because of the movement of many from their original contexts prior to archaeological investigation. Most have been dated to the Early Preclassic period (1500–1000 BC) with some to the Middle Preclassic (1000–400 BC) period. The smallest weigh 6 tons, while the largest is variously estimated to weigh 40 to 50 tons, although it was abandoned and left unfinished close to the source of its stone.
The colossal heads cannot be precisely dated. However, the San Lorenzo heads were buried by 900 BC, indicating that their period of manufacture and use was earlier still. The heads from Tres Zapotes had been moved from their original context before they were investigated by archaeologists and the heads from La Venta were found partially exposed on the modern ground surface. The period of production of the colossal heads is therefore unknown, as is whether it spanned a century or a millennium. Estimates of the time span during which colossal heads were produced vary from 50 to 200 years. The San Lorenzo heads are believed to be the oldest, and are the most skillfully executed. All of the stone heads have been assigned to the Preclassic period of Mesoamerican chronology, generally to the Early Preclassic (1500–1000 BC), although the two Tres Zapotes heads and the La Cobata Head are attributed to the Middle Preclassic (1000–400 BC).
Olmec colossal heads vary in height from 1.47 to 3.4 metres (4.8 to 11 ft) and weigh between 6 and 50 tons. All of the Olmec colossal heads depict mature men with flat noses and fleshy cheeks; the eyes tend to be slightly crossed. The general physical characteristics of the heads are of a type that is still common among people in the Olmec region in modern times. The backs of the heads are often flat, as if the monuments were originally placed against a wall. All examples of Olmec colossal heads wear distinctive headdresses that probably represent cloth or animal hide originals. Some examples have a tied knot at the back of the head, and some are decorated with feathers. A head from La Venta is decorated with the head of a bird. There are similarities between the headdresses on some of the heads that has led to speculation that specific headdresses may represent different dynasties, or perhaps identify specific rulers. Most of the heads wear large earspools inserted into the ear lobes.
All of the heads are realistic, unidealised and frank descriptions of the men. It is likely that they were portraits of living (or recently deceased) rulers well known to the sculptors. Each head is distinct and naturalistic, displaying individualised features. They were once thought to represent ballplayers although this theory is no longer widely held; it is possible, however, that they represent rulers equipped for the Mesoamerican ballgame.Expressions depicted on the heads vary from stern through placid to smiling. The most naturalistic Olmec art is the earliest, appearing suddenly without surviving antecedents, with a tendency towards more stylised sculpture as time progressed. Some surviving examples of wooden sculpture recovered from El Manatí demonstrate that the Olmecs are likely to have created many more perishable sculptures than works sculpted from stone.
Although all the colossal heads are broadly similar, there are distinct stylistic differences in their execution. One of the heads from San Lorenzo bears traces of plaster and red paint, suggesting that the heads were originally brightly decorated. Heads did not just represent individual Olmec rulers; they also incorporated the very concept of rulership itself.
Heads have been found in San Lorenzo, La Venta, Tres Zapotes, La Cobata, and Takalik Abaj.