In Pacific Rim (2013) the Kaijus share a hive (collective) mind. Through a hive mind system, the Kaiju can communicate instantly.
In Robotech (1985) The Invids are a hive-mind race that is driven by the need to take back what was stolen from them.
In The Last Question (1956) by Isaac Asimov, Man mentally was one. He consisted of a trillion, trillion, trillion ageless bodies, each in its place, each resting quiet and incorruptible, each cared for by perfect automatons, equally incorruptible, while the minds of all the bodies freely melted one into the other, indistinguishable.
All those stories portray collective minds or hive minds. But which story was the first to feature this idea?