"Yaji Ash-Shuthath," meaning "There is no peace at the gates".
It was an All-in-One and One-in-All of limitless being and self — not merely a thing of one Space-Time continuum, but allied to the ultimate animating essence of existence's whole unbounded sweep — the last, utter sweep which has no confines and which outreaches fancy and mathematics alike. It was perhaps that which certain secret cults of earth have whispered of as YOG-SOTHOTH, and which has been a deity under other names; that which the crustaceans of Yuggoth worship as the Beyond-One, and which the vaporous brains of the spiral nebulae know by an untranslatable Sign...
Did we forget "Q" and the "Continuum" ? What a guy, or is this other Star Trek?
Of course the Ancients and Old Ones, but they're gone some way or another.
Evolve, travel away(leave), die out.
The Continuum is indelible ink, always there.
No B5 aliens listed? Oh dear, that makes it difficult. Personally I foind myself torn on this - my favourite B5 entity was Kosh. His enigmatic utterances took some unravelling but were usually straight to the point. My favourite B5 utterance - G'Kar's famous "No one here is exactly as they seem."