The aviator is a sort of close relative to the adventurer. They spend their days up in the air in their airships and their planes, traveling to new frontiers and experience the sort of freedom you just can't get on the ground. The adventurer and the aviator can also be seen together in one character: after all, it takes an adventurous soul to want to get into one of those things. Some examples of aviators in general fiction include Manfred von Richtofen (who also happens to be a real person) in "The Red Baron" and the members of the Lafayette Escadrille in "Flyboys".
The Air Pirate
Now, I know that this kind of messes up the alphabetical order of the list, but with the aviator and the air pirate being so close, it made more sense to me to put them together. With all that air travel going on, you've got to have some people ready to line their pockets with stolen goods and such. That's where these guys come in. The air pirates can be seedy, sophisticated, anything, but they all share one common love: raiding ships. Their reasons, of course, can be as diverse as the pirates, themselves. Since these are kind of unique to steampunk, the main examples of these that I can think of are from steampunks. My personal favorite is Mr. Silver from "Treasure Planet".
The Femme Fatale
These are the deadly ladies of the steampunk genre. They aren't you're pretty society gals that sit around and look pretty like they're supposed to. They're out there trying to get what they want by just about any means necessary, and their particular goals are going to change depending on the lady. Some general examples of femme fatales include Irene from "Sherlock Holmes" (specifically the Robert Downey Jr. one) and Helga from "Atlantis".
So, some people put the mechanic and the scientist together into one archetype, but I kind of feel like they're different enough to be their own separate things. I kind of feel like the mechanic is a little more rugged than the scientist, usually. The main point of them, though, is that they're curious and want to know what makes things tick. The mechanic loves taking things apart, seeing how they work, and putting them back together. Overall, they're tinkerers, which I think is one of the things that sets them apart from the scientist. Some examples of this include Audrey from "Atlantis" and Winry from "Fullmetal Alchemist".
The Military Man/Woman
Since the Victorian era had a couple wars (most notably the Civil War in the US, and depending on how far forward you go and still consider it a steampunk, WW1), you're going to run into a lot of military types. The two main types of military men are the stiff, highly disciplined man, and the rugged, rebel without a cause type. They're generally men, but there's still plenty of women in this archetype, too. Think Mustang from "Fullmetal Alchemist" or Captain America.
So, this one kind of comprises of a few different archetypes you see in other genres, including the assassin, the mobster, the hunter, the con-artist etc. For our purposes, I've kind of combined all of these into one main archetype: the rogue. What these guys all have in common is that they kind of live on the outside of mainstream society. They're the loners, the social outcasts, the kind of people the average person in steampunk society doesn't really want to be associated with. And, frankly, a lot of these people are just fine with that. You see a lot of very rugged men (and women) falling in this category, and a lot of more anti-hero types tend to fall in this category. They come in all shapes and sizes, and can even cross socio-economic lines. Some examples of this archetype in general fiction include Ishmael from "Moby Dick" and Vin from Brandon Sanderson's "Mistborn Trilogy".
A very close relative to the mechanic, the scientist is a very curious character that loves pushing the bounds of science and discovering new things. Like the mechanic, they like seeing how things tick, but they tend to do it in a different way. The scientist is all about the scientific method, including relegating themselves to libraries to research, accidentally singing his eyebrows off in an attempt to find an elixir that could be used to eradicate tetanus, and long hours away from society to try and find the discovery that could change human kind. Of course, they tend to be a little eccentric, and can be asocial. Examples of the scientist type include Milo from "Atlantis" and Dr. Emmet Brown from "Back to the Future".
Well, that's what I can think of, for now. I'll add more as I think of more.
Now, rather than decide on my own what we should talk about, I'm going to let you, the readers, decide. I've covered what I think are the most important points of steampunk: now, I want to hear what you want to know. What should I cover, now? Share your opinion in the comments, and I'll talk about the most requested item next week.