In Part One we reviewed some of the common themes in 40K names for units and groups.
In Part Two we looked at naming themes within different races, such as with vehicles and weapons.
In Part Three we'll look at some places to find inspiration for names, particularly for characters.
General - With any name, if the one you're looking at doesn't quite fit or if you don't want to do a direct copy, mix it up a bit. For example, my Imperial Guard was painted to sort of look like WWII Americans, and I wanted a name that fit with that. So, I decided to call them the "Merkans", and made them the 76th, evoking 1776.
Regular names - For some things, this will be the natural choice. Naming normal folks like Guardsmen you probably don't want something like "Gibroth, Shatterer of Worlds", unless you've got a very unusual regiment. Sites for baby names like THIS or THIS can help you browse for ideas, including noting meanings for names in case you're going for a certain effect. Many sites also let you search by origin, letting you cruise for Norse, Greek, etc. names if you're going for a theme, like if you're looking for good Space Wolf names.
Other good sources for regular names are in the regular world. Flip through phone books, pick a non fiction book up and look at names of authors cited, look at the credits for a game book, check out the friends of friends on Facebook, etc.
History - Mostly regular names, but sometimes they may have a certain resonance or attached meaning that you'll find useful. If you want a good name for your Knight Commander Pask stand-in, various historical tank commanders might suit your purposes. Again, if you have a particular theme in mind, flip through histories of that country/region and see if anything grabs you. Not only names for individuals, but for groups can be useful too.
As an example, I painted up a Commissar Yarrick to go with my Merkan 76th Imperial Guard, but I wanted to name him something else. Given Yarrick's abilities to keep getting back up when "killed" I looked up people who got multiple Purple Hearts in WWII, and came across Robert T. Frederick, who got eight, among his other decorations. He's also the guy who commanded the Devil's Brigade (remember that movie?) among other things, so he should make for a pretty good Yarrick stand in IMO. Further bonus points for his name ending in -ick!
Scythians, who lived around the Black Sea/Caspian Steppe region. Not wanting to use the exact name, I mangled it a bit to Scythiak.
Mythology - Especially good for names of planets or Chaos Marines. I frequently use names of ancient gods for naming Chaos Marines aspiring champions like Anshar. GW use this principle themselves, with names like Nurgle.
The Bible/current religions - The Bible is an easy resource, chock full of great names. Again, good for Chaos Marines or anyone you want to give an old (testament) school feel to. GW themselves obviously pull a good deal from here and from other religiously associated names, with Baal, Azrael, Sammael, Astarte, etc. Just flip to a random section and go till you run into some great names, like Ezra 10.18-43. Bring on Jeremoth of Zattu!
Theme - Some armies lend themselves to particular names, like Nurgle armies making rot- or disease- associated names quite appropriate, such as the poster-boy, Typhus. Find a name for some icky disease and you're most of the way home naming a Nurgle character.
Other - Inspiration can strike from anywhere. Keep your eyes and ears open, and jot down anything you may want to use later!