As of 2015, the hottest chili pepper in the world is the Carolina Reaper. This chili clocks in at about 1.5 million Scoville Heat Units, which is the measurement for spiciness, on average. At its peak, the Carolina Reaper can reach up to 2.2 million SHU.
The Carolina Reaper is a cross between a Pakastani Naga and a Red Habanero. In addition to its extreme heat, connoisseurs say that it also has a good flavor.
Some other peppers that have extreme amounts of heat include the Trinidad Moruga Scorpion, peaking at over 2 million SHU, and the 7 Pot Douglah, peaking at over 1.85 million SHU.