Forerunners

The Forerunners were a foolish race that did absolutely nothing to help anyone. In fact, they just made everything worse and blew a tiny squabble WAY out of proportion.

They built the Halo Rings, which were designed to destroy the Flood by killing EVERYONE. Who does that?

They were basically wiped out in A War which started when they decided to bully the local wildlife of a newly discovered planet just because it wasn't as advanced as them. Turned out this wildlife was the Flood. Oops.

They at least decided to preserve specimens of life forms and keep them safe on the Ark so they could be saved and reseeded back into the Galaxy. Well, one of them did anyway...

They are similar in both appearance and fate to the Protheans. They were both races at their golden age millions of  years ago and were both wiped out in a mass extinction event. Unlike the Protheans, who possessed some degree of intelligence, The Forerunners destroyed themselves, whereas the Protheans actually had an excuse.

Notable Forerunners

 * The Librarian
 * The Didact
 * The Janitor

Notable Forerunner Creations

 * Halo Rings (Installation 04)
 * Monitors
 * Guilty Guilty, aka 343 Guilty Spark
 * 2401 Penitent Tangent
 * 049 Abject Testament
 * 007 Greenie Spark
 * Sentinels