The Mark X (Japanese: トヨタ・マークX) is a mid size automobile created by Toyota for the Japanese market. The Mark X was introduced in 2004 and is manufactured in Kanegasaki, Iwate, Japan. Also sold in China as the Reiz, it is available with either a 253horsepower (189kW) 3.0 L or 212horsepower (158kW) 2.5 L GR series V6 engine. Both engines offer dual VVT-i (variable valve timing) with gasoline direct injection(Japanese models only). The rear-wheel drive models have a 6-speed automatic transmission as standard, and the all-wheel drive models have a 5-speed automatic.

The Mark X is the successor to the Mark II which was first introduced in 1968, was known in the North American market as the Corona Mark II starting in 1972 and the Cressida from 1977 to 1992 and was the predecessor to the introduction of Lexus. Although the vehicle features an impressive interior with quality that can be categorized as a luxury sedan, it is aimed at the middle market. The Mark X is not pronounced "Mark Ten" but "Mark ecks" (pronounced /ɛks/) though the Mark II is "Mark Two".

Minor changes were made in 2006. Mirror mounted turn signals replaces the fender mounted turn signal, and a redesign grille. Mark X with all black interior deleted the wood trim in favor of the brush aluminum trim. A formal introduction of the "S package" which gain the 3-spoke steering wheel and changes to the exterior lip piece.

The Mark X Supercharged version uses the 3GR-FSE engine. Power output is 316horsepower (236kW) at 6200 rpm and 42.0kilogram metres (412N·m; 304ft·lbf) at 3200 rpm, paired to a 6 speed auto transmission.