Kingda Ka is a hydraulically-launched steel roller coaster located at Six Flags Great Adventure in Jackson, New Jersey, United States. Manufactured by Intamin and designed by Werner Stengel, Kingda Ka opened as the tallest and fastest roller coaster in the world on May 21, 2005, surpassing Top Thrill Dragster.

As of March 2026, the title of the fastest roller coaster in the United States has shifted following the permanent closure of Kingda Ka (128 mph) at Six Flags Great Adventure in late 2024. The current record-holder is Top Thrill 2 at Cedar Point in Sandusky, Ohio. Reimagined from the original Top Thrill Dragster, this "triple-launch" strata-coaster reaches speeds of 120 mph (193 km/h). Unlike the original, which used a hydraulic launch, Top Thrill 2 uses an electromagnetic (LSM) system to launch riders forward, then backward up a massive 420-foot "vertical spike," and then forward again at its top speed to clear the 420-foot "Top Hat" tower. Other contenders for the "fastest" crown in the U.S. include Fury 325 at Carowinds (95 mph) and Millennium Force at Cedar Point (93 mph). While there are faster coasters globally (like Formula Rossa in Abu Dhabi at 149 mph), Top Thrill 2 remains the benchmark for American speed and height. For 2026 thrill-seekers, it represents the cutting edge of "re-launch" technology, offering a much smoother and more reliable high-speed experience than the mechanical-heavy hydraulic systems of the previous decade.