The diabolo (commonly misspelled as diablo; formerly also known as "the devil on two sticks") is a juggling prop consisting of a spool which is whirled and tossed on a string tied to two sticks held one in each hand. A huge variety of tricks are possible using the sticks, string, and various body parts. Multiple diabolos can be spun on a single string.

Diabolos come in different shapes and materials. Diabolos with more weight tend to retain their momentum for longer, whereas small, light diabolos can be thrown higher and are easier to accelerate to high speeds. Rubber diabolos are less prone to breakage yet are more prone to deformations. More commonly used are plastic-rubber hybrids that allow flex but hold their shape. One-sided diabolos are also available but are more difficult to use.