As of January 2022, here are some of the biggest roller coasters in the world based on various criteria such as height, speed, length, and other features:
1. Kingda Ka - Located at Six Flags Great Adventure in New Jersey, USA, Kingda Ka is currently the tallest roller coaster in the world. It stands at a height of 456 feet (139 meters) and reaches speeds of up to 128 miles per hour (206 kilometers per hour). It also features a vertical drop of 418 feet (127 meters).
2. Formula Rossa - Located at Ferrari World Abu Dhabi in the United Arab Emirates, Formula Rossa is the fastest roller coaster in the world. It accelerates from 0 to 149 miles per hour (240 kilometers per hour) in just 4.9 seconds. Formula Rossa is known for its Formula One-themed experience and its top speed.
3. Steel Dragon 2000 - Located at Nagashima Spa Land in Japan, Steel Dragon 2000 held the record for the longest roller coaster in the world when it opened in 2000. It spans a length of 8,133 feet (2,479 meters) and reaches a maximum height of 318 feet (97 meters). It offers a thrilling ride experience with its extensive layout.
4. Top Thrill Dragster - Similar to Kingda Ka, Top Thrill Dragster is located at Cedar Point in Ohio, USA. It was the first roller coaster to surpass the 400-foot (122-meter) height threshold when it opened in 2003. It reaches a height of 420 feet (128 meters) and accelerates to speeds of up to 120 miles per hour (193 kilometers per hour).
5. Steel Vengeance - Also located at Cedar Point in Ohio, USA, Steel Vengeance is known for its hybrid design, combining a wooden structure with steel tracks. It holds the record for the tallest and fastest hybrid roller coaster, with a height of 205 feet (62 meters) and a top speed of 74 miles per hour (119 kilometers per hour).
6. Fury 325 - Located at Carowinds in North Carolina and South Carolina, USA, Fury 325 is currently the tallest and fastest giga coaster in the world. It stands at a height of 325 feet (99 meters) and reaches speeds of up to 95 miles per hour (153 kilometers per hour). It offers a thrilling ride experience with its steep drops and high speeds.
7. Millennium Force - Also located at Cedar Point in Ohio, USA, Millennium Force was the first roller coaster to exceed 300 feet (91 meters) in height when it opened in 2000. It stands at a height of 310 feet (94 meters) and reaches speeds of up to 93 miles per hour (150 kilometers per hour).
These are just a few examples of some of the biggest roller coasters in the world. Roller coaster records may change over time as new coasters are built and existing ones are modified. Always check the latest information from reliable sources and theme park websites for the most up-to-date records and ride experiences.