原蜻蜓目（学名Protodonata或Meganisoptera）是一目已灭绝及体型非常巨大的古生代昆虫，外观有点像及接近现今的蜻蜓。牠们包括已知最大的昆虫，如晚石炭纪的巨脉蜻蜓、Megatypus及早二叠纪的Meganeuropsis。

除了在后翅近臀部的位置外，原蜻蜓目的前后翅膀有相似的脉纹。前翅一般都较后翅幼长。

大部份标本都只有翅膀碎片，只有少量是完整的翅膀，有身体轮廓的则更少。这些轮廓显示原蜻蜓目有球状的头，头上有齿状的颌，粗壮的脚有刺，大的胸腔及幼长像蜻蜓的腹部。

虽然有时原蜻蜓目被包括在蜻蜓目中，但牠们却没有一些蜻蜓目的特征，故此一般称原蜻蜓目为「巨大蜻蜓」会令人误解。

Meganisoptera is an extinct order of very large to gigantic insects, occasionally called griffinflies. The order was formerly named Protodonata, the "proto-Odonata", for their similar appearance and supposed relation to modern Odonata (damselflies and dragonflies). They range in Palaeozoic (Late Carboniferous to Late Permian) times. Though most were only slightly larger than modern dragonflies, the order includes the largest known insect species, such as the late Carboniferous Meganeura monyi, Megatypus, and the even larger early Permian Meganeuropsis permiana, with wingspans of up to 71 centimetres (28 in).