The Lexus RX is a mid-size luxury crossover SUV produced by Toyota Motor Corporation. In North America, Europe, Oceania, and parts of Asia, including Singapore as a 2003 introduction and Japan as a 2008 introduction, it is sold by Lexus, Toyota's luxury division, as the Lexus RX series (such as the RX 300, RX 330 and RX 350). It is currently sold in Japan and previously in Singapore as the Toyota Harrier.

The RX first premiered in 1997 as a Lexus concept, followed several months later by debut of the production RX 300/Harrier models. In 2003, the second generation RX debuted in the U.S., and the redesigned RX 330/Harrier went on sale shortly after. In 2004, the RX line added the world's first luxury-type hybrid, the RX 400h, and the RX 330 was upgraded to the RX 350 for model year 2007.

As one of the first luxury SUVs on the market, the Lexus RX has inspired similar competitors from rival marques. Its commercial success as Lexus' best-selling model has been attributed to the strong reliability reputation of Lexus and the RX line, and it has been the best-selling luxury vehicle in the United States. The RX is also the only Lexus vehicle to be produced outside of Japan, being made at the Cambridge plant in Canada.