Pentium D is a series of microprocessors introduced by Intel at the Spring 2005 Intel Developer Forum. A Pentium D chip consists of two Pentium 4 Prescott processors on a single die.

The Pentium D was the first announced multicore CPU (along with its more expensive twin, the Pentium Extreme Edition) from any manufacturer for desktop computers. Intel underscored the significance of this introduction by predicting that by the end of 2006, over 70% of its shipping desktop CPUs would be multicore. Analysts have speculated that the clock rate race between Intel and AMD is largely over, with no more exponential gains in clock rate looking likely. Instead, as long as Moore's Law holds up, it is expected that the increasing numbers of transistors that chip-makers can incorporate into their CPUs will be used to increase CPU throughput in other ways, such as by adding cores, as the Pentium D does.

As with a multiprocessor PC, the Pentium D provides significant performance improvement only with applications that have been written specifically for multiple CPUs or cores — such as most 3D rendering programs and video encoders — and in heavy multitasking situations where the PC user is running several CPU-heavy applications, and each core can handle a different application. Most business applications and games as of 2005 only use a single thread, so for these applications running alone, the Pentium D will deliver largely the same performance as an older Pentium 4 running at the same clock rate.