Omniscient narrator
A narrator who knows everything about the story and its characters, and may comment, judge, anticipate.
The omniscient narrator combines all knowledge (see zero focalization) and, often, a voice of its own: commenting on the action, judging characters, addressing the reader, generalizing ("all happy families are alike…"). Not a character — but a presence.
That overview has a codified counterpart: what the omniscient narrator asserts is held true. It cannot lie — only withhold. That's why suspense in omniscience rests on owned retention, and why confusing the omniscient narrator with a mistaken character produces a feeling of cheating in the reader.
Example
Tolstoy's narrator opens Anna Karenina with a maxim about all families.