Hughes Reef (Mandarin Chinese: 東門礁/东门礁; pinyin: Dōngmén Jiāo, Vietnamese: đá Tư Nghĩa) is a reef in Union Banks in the Spratly group of islands, South China Sea claimed by the PRC (China), the ROC (Taiwan), the Philippines, Malaysia, and Vietnam. It is only above water at low tide.

The PRC has reclaimed land on the reef, bringing its area to 7.6 hectares, and occupied the reef. The reef has a lighthouse on top of a two storied defence outpost.