Walkers are alien machines in the 2005 film H.G. Wells' War of the Worlds, which came out the same year as the Spielberg version. They are 6 legged death machines which go up to 60 feet in height and are dark brown in color. The aliens that control them are light green crab-like aliens with four legs instead of Wells idea of them being plump octopus looking martians.
The walkers kill anything in their path and spread a poisonus gas that looks like a green cloud which is used to kill smaller animals like rabbits and such. Their death beam turns humans into Skeletons and there is no explanation yet to what they do with the earthlings flesh.
The walkers also have weapons which come out from their sides like saws and beams which are used to slice open people.