The giant hawker (Tetracanthagyna plagiata) or the gigantic riverhawker, is a species of dragonfly in the family Aeshnidae. It is found throughout Sundaland, having been recorded on Thailand, Peninsular Malaysia, Singapore, Sumatra, and Borneo. It is the type species for the genus Tetracanthagyna.

It is the heaviest of all living Odonata, and additionally are the second largest of all living Odonates by wingspan, second only to Megaloprepus caerulatus (Pseudostigmatidae). T. plagiata is additionally the largest living dragonfly, with a maximum wingspan of 163 millimetres (6.42 in), exceeding the wingspan of runner-up Petalura ingentissima at 162 millimetres (6.38 in).

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