The Malaysian giant katydid is the largest katydid insect in the world.
Giant Katydid (Macrolyristes Corporalis) in the Malayan woods exhibit in the Toronto Zoo.
It can grow up to 15cm long. Some people like to keep this insect as a pet. I guess it is interesting to look at or even hold in your hand since it is so large for an insect.
If you are thinking about getting one, beware! Apparently giant katydids chirp — not surprising they are after all close relatives of the crickets, bush crickets being another name for katydids — and they have a sound proportional to their size, so think twice before getting one as a pet. Here is a YouTube video by the Cincinnati Zoo about their Giant Katydid including the chirping noise.
Another giant katydid.
The Malaysian giant katydid lives on a vegetarian diet, and in the food chain it is usually the other animals who try to eat it. Only the sharp spikes on its leg provide some protection against less determined predators.
Further Readings:
Largest Species Of Katydid In The World