广翅鲎（学名：Eurypterid）又名板足鲎、海蝎，是一类已灭绝的节肢动物，大约有300种已知的广翅鲎。

诞生于奥陶纪，距今约4亿6000万-4亿4500万年前，繁盛于志留纪，灭绝于二叠纪-三叠纪灭绝事件。大约生存了2.5亿年。

Eurypterids (sea scorpions) are an extinct group of arthropods that are related to arachnids and include the largest known arthropods to have ever lived. They are members of the extinct order Eurypterida (Chelicerata); which is the most diverse Paleozoic chelicerate order in terms of species. The name Eurypterida comes from the Greek words eury- (meaning "broad" or "wide") and pteron (meaning "wing"). This name was chosen due to the pair of wide swimming appendages on the first fossil eurypterids discovered. The largest, such as Jaekelopterus, reached 2.5 metres (8 ft 2 in) in length, but most species were less than 20 centimetres (8 in). They were formidable predators that thrived in warm shallow water, in both seas and lakes, from the mid Ordovician to late Permian (470 to 248 million years ago).