"Nocturne" is a Latin word derived from "nox, noctis" meaning "night". Nocturne can be loosely translated to "by the night".
In French, a nocturne is usually a musical composition that is inspired by, or evocative of, the night. Historically, nocturne is a very old term applied to Night Offices and, since the Mid Ages, to divisions in the canonical hour of Matins.
In French, nocturne is also an adjective to describe living entities who are active at night.
Umbra, the Latin word for "shadow", is the darkest part of the shadow, where the light source is completely blocked by the occluding body. An observer in the umbra experiences a total eclipse.
Nocturne was the first champion to be previewed on a popular event prior to its release, namely at the PAX East 2011.
He was also given a small sneak peek on the website IGN before release.
Nocturne's ultimate Paranoia was the name of Fiddlesticks' original passive, which caused enemies nearby to miss their attacks.
Haunting Nocturne had its Duskbringer and Unspeakable Horror ability particles changed from the original's black to slime green after a petition on the League of Legends forum by players as seen here.
Haunting Nocturne's art was used for the log in screen during The Harrowing of 2011.
Nocturne's general theme bears some resemblence to the NecronWraith and one of the Necron's Star Gods, the Nightbringer. This is particularly prevalent in his Eternum skin, where he also also draws some similarities to another Star God, the Deceiver.
Eternum Nocturne's color pallet and somewhat electronic spell effects resemble the Battlecast skins.
Eternum Nocturne's voice and demeanor are similar to Harbinger from the Mass Effect series.
He also bears some resemblance to the Human-Reaper, although it might be more appropriate to say both the Human-Reaper and Nocturne resembles half a human skeleton.