Farmall was a model name and later a brand name for tractors manufactured by International Harvester (IH). The Farmall name was usually presented as McCormick-Deering Farmall and later McCormick Farmall in the evolving brand architecture of IH.

Farmalls were general-purpose tractors. Their origins were as row-crop tractors, a category that they helped establish and in which they long held a large market share. During the decades of Farmall production (1920s to 1970s), most Farmalls were built for row-crop work, but many orchard, fairway, and other variants were also built. Most Farmalls were all-purpose tractors that were affordable for small to medium-sized family farms and could do enough of the tasks needed on the farm that the need for hired hands was reduced and the need for horses or mules was eliminated. Thus Farmall was a prominent brand in the 20th-century trend toward the mechanization of agriculture.

The original Farmall was the first general-purpose tractor with narrowly spaced front wheels ('tricycle' configuration) and added ground clearance, making it one of the first row-crop tractors. These design traits allowed for more nimble maneuvering and accurate cultivation than many other tractors of the day, yet the Farmall could also, like previous tractors, perform all the other duties a farmer would have previously achieved using a team of horses. (A tractor could even do some novel tasks besides.) A tractor could yield lower overall operating costs than horses as long as it was priced right and reliable (and its fuel supply as well). The Farmall, mass produced with the same low-cost-and-high-value ethos as the Ford Model T or Fordson tractor, could meet that requirement. The Farmall was thus similar to a Fordson in its capabilities and affordability, but with better cultivating ability.

Descriptions of tractors as "general-purpose" and "all-purpose" had been used loosely and interchangeably in the teens and early twenties; but a true all-purpose tractor would be one that not only brought power to ploughing, harrowing, and belt work but also obviated the horse team entirely. This latter step is what changed the financial picture to heavily favor the mechanization of agriculture. The Farmall was so successful at total horse replacement that it became a strong-selling product. With the success of the Farmall line, other manufacturers soon introduced similar general- to all-purpose tractors with varying success.

In later decades, the Farmall line continued to be a leading brand of all-purpose tractors. Its bright red color was a distinctive badge. During the 1940s and 1950s, the brand was ubiquitous in North American farming. Various trends in farming after the 1960s—such as the decline of cultivating in favor of herbicidal weed control, and the consolidation of the agricultural sector into larger but fewer farms—ended the era of Farmall manufacturing. However, many Farmalls remain in farming service, and many others are restored and collected by enthusiasts. In these respects, the Farmall era continues. As predicted in the 1980s and 1990s, the growing public understanding of environmental protection, and of sustainability in general, have brought a corollary resurgence of interest in organic farming and local food production. This cultural development has brought a limited but notable revival of cultivating and of the use of equipment such as Farmalls.

 Case IH was formed when the Agricultural Division merged with J.I. Case.