Prometheus (recorded as WPN-114) was the world's oldest known non-clonal organism, a Great Basin bristlecone pine (Pinus longaeva) tree growing near the tree line on Wheeler Peak in eastern Nevada, United States. The tree, which was at least 4,862 years old and possibly more than 5,000, was cut down in 1964 by a graduate student and United States Forest Service personnel for research purposes. Those involved did not know of its world-record age before the cutting, and the circumstances and decision-making process remain controversial.

The tree's name refers to the mythological figure Prometheus, who stole fire from the gods and gave it to man. The designation WPN-114 was given by the original researcher, Donald Rusk Currey, and means it was the 114th tree he sampled in his research in Nevada's White Pine County.

Prometheus (WPN-114) was a living member of a population of bristlecone pine trees near the tree line on the lateral moraine of a former glacier on Wheeler Peak, in Great Basin National Park, eastern Nevada. Wheeler Peak is the highest mountain in the Snake Range, and the second highest mountain in the state of Nevada. The bristlecone pine population on this mountain is divided into at least two distinct sub-populations, one of which is accessible by a popular interpretive trail.

Prometheus, however, grew in an area reachable only by off-trail hiking. In either 1958 or 1961, a group of naturalists who admired Prometheus's grove gave names to a number of the largest or most distinctive trees, including Prometheus.

Currey originally estimated the tree was at least 4,844 years old. A few years later, this was increased to 4,862 by Donald Graybill of the University of Arizona's Laboratory of Tree-Ring Research. These ring counts were done on a trunk cross-section taken about 2.5 m (8 feet) above the original germination point of the tree, because the innermost rings were missing below that point. Adjusting Graybill's figure by adding the estimated number of years required to reach that height, plus a correction for the estimated number of missing rings (not uncommon in trees at the tree line), it is probable that the tree was at least 5,000 years old when it was cut down. That made it the oldest known unitary (i.e. non-clonal) organism at the time, exceeding even the Methuselah tree of the White Mountains' Schulman Grove, in California, though Methuselah was later redated to 4,850 years old.

In 2010, a reportedly living bristlecone pine in California's White Mountains was measured by Tom Harlan to be 5,062 years old. This pine has not been found after Harlan's death in 2013, and its core has not been located at the Laboratory of Tree-Ring Research.

Whether Prometheus should have been considered the oldest organism ever known depends on the definition of "oldest" and "organism". Certain sprouting (clonal) organisms, such as creosote bush or aspen, may be considered older if the entire clonal organism is considered. By that standard, the oldest living organism is a grove of quaking aspens in Utah known as Pando, at perhaps as much as 80,000 years old, although likely much less. In a clonal organism, however, the individual clonal stems are not nearly so old, and no part of the organism is particularly old at any given time. Until 2012, Prometheus was thus the oldest non-clonal organism yet discovered, with its innermost, extant rings exceeding 4862 years of age.

In the 1950s, dendrochronologists were making active efforts to find the oldest living tree species. They intended to analyze the rings for various research purposes, such as evaluation of former climates, dating of archaeological ruins, and addressing the basic scientific question of maximum potential lifespan. Bristlecone pines in California's White Mountains and elsewhere were discovered by Edmund Schulman to be older than any species yet discovered. This spurred interest in finding very old bristlecones, possibly older than the Methuselah tree, aged by Schulman in 1957 at over 4,700 years.