Phoenician nun — "fish" or "snake", through Greek nu.
N
the same word nun survives in the Hebrew and Arabic alphabets to this day, with the same sound and — in the old abjad order that both inherited — the same position.
Allen · Anderson · Andrews · Armstrong · Arnold · Barnes · Bennett · Bevan · Bianchi · Braun · Brennan · Brown · Burns · Byrne
In the modern alphabet this letter is number 14 of 26. Before it comes M, after it O. The order itself is inherited: Latin took it from Greek, Greek from Phoenician, and the sequence has survived largely unchanged for about three thousand years. Every rearrangement since has been an insertion, not a reshuffle.
This is a consonant: it sets the hardness of a name and how it meets the next word. In a corpus of 315 surnames this letter opens 7 and closes 57. Among the 96 given names in the base it appears in 35. The surname carrying the most of it is Brennan, with 3.
John · Daniel · Anthony · Steven · Andrew · Nicholas · Benjamin · Alexander · Henry · Nathan · Sean · Ethan
These letters came from the Greek alphabet.