Pentium is a series of x86 architecture-compatible microprocessors produced by Intel from 1993 to 2023. The original Pentium was Intel's fifth generation processor, succeeding the i486; Pentium was Intel's flagship processor line for over a decade until the introduction of the Intel Core line in 2006. Pentium-branded processors released from 2009 onwards were considered mid-range budget products positioned above the entry-level Atom and Celeron series, but below the faster Core lineup and workstation/server Xeon series.

The later Pentiums, which have little more than their name in common with earlier Pentiums, were based on both the architecture used in Atom and that of Core processors. In the case of Atom architectures, Pentiums were the highest performance implementations of the architecture. Pentium processors with Core architectures prior to 2017 were distinguished from the faster, higher-end i-series processors by lower clock rates and disabling some features, such as hyper-threading, virtualization and sometimes L3 cache. In 2017, the Pentium brand was split up into two separate lines using the Pentium name: Pentium Silver, aiming for low-power devices using the Atom and Celeron architectures; and Pentium Gold, aiming for entry-level desktop and using existing architectures such as Kaby Lake or Coffee Lake.

In September 2022, Intel announced that the Pentium and Celeron brands were to be replaced with the new "Intel Processor" branding for low-end processors in laptops from 2023 onwards. This applied to desktops using Pentium processors as well, and was discontinued around the same time laptops stopped using Pentium processors in favor of "Intel Processor" processors in 2023.

During development, Intel generally identifies processors with codenames, such as Prescott, Willamette, Coppermine, Katmai, Klamath, or Deschutes. These usually become widely known, even after the processors are given official names on launch.

The original Pentium-branded CPUs were expected to be named 586 or i586, to follow the naming convention of prior generations (286, i386, i486). However, as the firm wanted to prevent their competitors from branding their processors with similar names (as AMD had done with their Am486), Intel filed a trademark application on the name in the United States, but was denied because a series of numbers was considered to lack trademark distinctiveness. Instead, they would name their processors as "Pentium" rather than using numbers, which Andrew Grove wanted to trademark that generation processor.

Following Intel's prior series of 8086, 80186, 80286, 80386, and 80486 microprocessors, the firm's first P5-based processor was released as the original Intel Pentium on March 22, 1993. Marketing firm Lexicon Branding was hired to coin a name for the new processor. The suffix -ium was chosen as it could connote a fundamental ingredient of a computer, like a chemical element, while the prefix pent- could refer to the fifth generation of x86.

Due to its success, the Pentium brand would continue through several generations of high-end processors. In 2006, the name briefly disappeared from Intel's technology roadmaps, only to re-emerge in 2007.

In 1998, Intel introduced the Celeron brand for low-priced processors. With the 2006 introduction of the Intel Core brand as the company's new flagship line of processors, the Pentium series was to be discontinued. However, due to a demand for mid-range dual-core processors, the Pentium brand was repurposed to be Intel's mid-range processor series, between the Celeron and Core series, continuing with the Pentium Dual-Core line.