In the mirror universe, Doctor Leonard H. McCoy was a Human Starfleet officer who served as chief medical officer aboard the ISS Enterprise in the 2260s. In 2266, McCoy spilled acid on a lab table in sickbay. In contrast to the primary universe, the stain was not cleaned and remained until at least another year. McCoy eventually died in 2269/2270 of the fatal disease known as xenopolycythemia, indicating that in the mirror universe, either the Enterprise crew never encountered Yonada, or they simply destroyed the vessel.