A parcel bomb (or letter bomb) is an explosive device which is disguised to look like a normal, mailed article, which can be sent through the normal postal service or delivered via courier. Parcel bombs are usually set to explode immediately on opening, with the intention of seriously injuring or killing the recipient (who may or may not be the person to which the bomb was addressed).

Parcel bombs have been used in terrorist campaigns, such as that of the Unabomber.