What Could Have Been: According to a post from Nightmargin, Niko's name was originally "Nico", but was changed to "Niko" in reference to Nikola Tesla and his work on lightbulbs. This ended up working out very well, as the Japanese word for sunlight is 日光, romanized as Nikko.
Word of God: The various NPCs Niko runs into have names according to Night's tumblr. These actually show up in dialogue in the updated re-release, and some of them were changed: