Penghu 1 is a fossil jaw (mandible) belonging to an extinct hominin species of the genus Homo from Taiwan which lived in the middle-late Pleistocene. The precise classification of the mandible is disputed, some arguing that it represents a new species, Homo tsaichangensis, whereas others believe it to be the fossil of a H. erectus, an archaic H. sapiens or possibly a Denisovan.

The fossil was recovered sometime before 2008 by fishermen working in the Penghu Channel between the Penghu Islands and mainland Taiwan and acquired by Tainan citizen Mr. Kun-Yu Tsai. The fossil was found 60–120 meters below the water's surface and about 25 kilometers off the western coast of Taiwan in an area that was once part of the mainland. Sea levels have risen since the last ice age and in consequence, have submerged the area where the fossil was recovered. After Mr. Tsai donated the fossil to the National Museum of Natural Science, it was described in 2015 by an international team of Japanese, Taiwanese, and Australian scientists.

Penghu 1 is currently housed at the National Museum of Natural Science in Taichung.

The fossil is stratigraphically dated to be younger than 450 kya, based on prehistoric sea-level lowering to either between 190 and 130 kya or between 70 and 10 kya.

The fossil consists of a nearly complete right lower jaw with four teeth, including worn molars and premolars. The mandible has a high index of robustness, a robust lateral torus, and large molars, and with the help of 3D reconstruction, it was revealed to have a large bicondylar breadth. These features help confirm that the fossil was from the middle-late Pleistocene era. The alveoli of its four incisors and right canine have been preserved as well showing their great length. The specimen was assigned to the genus Homo based on its jaw and tooth morphology. The mandible shows a receding anterior surface and lacks a pronounced chin which has helped distinguish it from the species Homo sapiens. However, the fossil exhibited derived traits similar to early Homo habilis including the shortness and width of its jaw. These and other characteristics such as the agenesis of the M3 molar have been sufficient enough evidence to classify the specimen of the genus Homo.