These two genres are very closely related and since I'm not entirely certain what qualifies as Steampunk, I have a mix of both kinds in here. I'll indicate (with a *) what I think (and others think) is Steampunk. For more Steampunk titles and fun, visit The Book Smugglers Steampunk Week posts.
Steampunk and Historical Fantasy
The Abhorsen trilogy by Garth Nix
Airborn, Skybreaker, and Starclimber by Kenneth Oppel*
Airman by Eoin Colfer*
Bewitching Season by Marissa Doyle
Boneshaker by Cherie Priest* (suggested by A Bookshelf Monstrosity)
The Boneshaker by Kate Milford* (suggested by Kate Coombs)
Candle Man by Glenn Dakin*
City of Ember by Jeanne DuPrau*
Dreamhunter and Dreamquake by Elizabeth Knox
Gemma Doyle trilogy by Libba Bray
His Dark Materials by Philip Pullman*
Horatio Lyle series by Catherine Webb* (Suggested by Court)
Jonathan Strange and Mr. Norrell by Susanna Clarke
Larklight by Philip Reeve*
Leviathan by Scott Westerfeld*
Magic Under Glass by Jaclyn Dolamore*
Mister Monday (Keys to the Kingdom series) by Garth Nix*
Mortal Engines Quartet by Philip Reeve*
Prophecy of the Sisters by Michelle Zink
Sent by Margaret Peterson Haddix
Silver Phoenix by Cindy Pon
Sorcery and Cecelia by Caroline Stevermeyer and Patricia C. Wrede
Soulless by Gail Carriger*
Temeraire by Naomi Novik*
Thirteenth Child by Patricia Wrede
Feel free to add your suggestions!
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