The Bond 

Because... James Bond! Ok, i admit it, this is is just a joke.

I actually like it out of a joke context. 

The common word bond may have a lot of significations. I was imaginating the things before opening your trhead :d

For instances :

An unmaterial evil faction bonding each other living being from darkness like a reverse religion/spiritual link... for mysterious reasons

Wraith creatures linked to each other via a bond because they have nothing else, so they name themselves the Bond (like a hive mind, or the protoss's khala, etc.)

Creature that are bond to the past, to the before the endless, that see themselves of the last link to the past universe...