It’s that time of year when many people are setting reading goals and looking for reading lists to expand their usual fare. If you are looking to read more science fiction or if you are using a reading list that asks you to read one science fiction novel and you don't know what to choose, I have made this list.

In my experience, often when people think of science fiction, they think of a narrow idea that they got from one or two books or movies. If they didn't like the first thing they were exposed to, they tend to dismiss the whole genre as bad. But science fiction is much broader than most people think. So let’s look at the various themes and some recommended reading to try in the different themes. Note that many books in science fiction have multiple themes. Many of the books listed are the first book or a series (occasionally a later book if the series as a whole doesn't fit the category).

Space opera - This is what many people think about when they think science fiction. It’s all about space ships, right? Space opera is the fun area of the field, it’s all about the adventure. Sure it is usually involving trips by space ship, but the real key is the adventure.. Star Wars is Space Opera, so are Firefly, Farscape, both versions of Battlestar Galactica and Star Trek. Since it is so common in movies and film, it is the most widely known type. There are plenty of books that are considered Space Opera, too.
 Have Spaceship Will Travel - Robert Heinlein
 Quarter Share - Nathan Lowell
 A Long Way to A Small Angry Planet - Becky Chambers
 Hunter of Worlds - C J Cherryh

Romance - Romance novelists sometimes set their books in space.
 Accidental Goddess - Linea Sinclair
 Gabriel’s Ghost - Linnea Sinclair
 A Civil Campaign - Lois McMaster Bujold
 Shards of Honor - Lois McMaster Bujold
 Primary Inversion - Catherine Asaro (This is also vary much a hard science fiction novel, the author has a PhD in Physics)
 Local Custom - Sharon Lee, Steve Miller
 Scout’s Progress - Sharon Lee, Steve Miller

Crime - Once you colonize other planets or build space stations that are permanent residences, eventually you have crime. Even on this planet in the future, crime will still be with us.
 I’ Robot - Isaac Azimov
 The Caves of Steel - Isaac Azimov
 The Down Home Zombie Blues - Linnea Sinclair
 Leviathan Wakes - James S. A. Corey
 The Demolished Man - Alfred Bester
 Altered Carbon - Richard Morgan
 The Disappeared - Kristine Kathryn Rusch
 The Stainless Steel Rat - Harry Harrison

Colonization - Colonizing another world brings inevitable problems
  Red Mars - Kim Stanley Robinson
 Dragonsdawn - Anne McCaffrey
 40,000 in Gehenna - C J Cherryh
 Freedom’s Landing - Anne McCaffrey
 Remnant Population - Elizabeth Moon
 Farmer in the Sky - Robert Heinlein
 Desolation Road - Ian McDonald
 The Moon is Harsh Mistress - Robert Heinlein

World Building - Epic in scale and loads of detail to make the universe seem very real
 The Sword of the Lamb - M.K. Wren
 Dune - Frank Herbert
 Foundation - Isaac Azimov
 Ringworld - Larry Niven

Aliens - Books that have aliens either meeting humans or in their separate planets
 Foreigner - C. J. Cherryh
 Enemy Mine - Barry Longyear
 The Three Body Problem - Cixin Liu
 Hunter of Worlds - C. J. Cherryh
 Little Fuzzy - H. Beam Piper
 The Faded Sun: Kesrith - C. J. Cherryh
 The Pride of Chanur - C. J. Cherryh
 Brothers of Earth - C. J. Cherryh

Post apocalyptic - what happens after a disaster happens
 The Postman - David Brin
 Canticle for Lebowitz - Walter Miller
 Dies the Fire - S. M. Stirling
 Alas Babylon - Pat Frank
 The Stand - Steven King
 Station Eleven - Emily St.John Mandel
 Eternity Road - Jack McDevitt
 Parable of the Sower - Octavia Butler
 Where Late the Sweet Birds Sang - Kate Wilhelm
 The Breaking of Northwall - Paul O. Williams

Time Travel - what happens after a time machine is invented
 Kindred - Octavia Butler
 In the Garden of Iden - Kage Baker
 The Time Machine - H. G. Wells
 The Time Traveller’s Wife - Audrey Niffenegger
 To Say Nothing of the Dog - Connie Willis
 The Doomsday Book - Connie Willis
 How to Live Safely in a Science Fictional Universe - Charles Yu

Medical Science fiction - Concerning medical practice or diseases
 The Andromeda Strain - Micheal Crichton
 General Practice - James White
 Moreta: Dragonlady of Pern - Anne McCaffrey
 Nerilka’s Story - Anne McCaffrey

Legal science fiction - Includes stories of lawyers, and/or world-building concerning particular types of laws
 A Just Determination - John G. Hemry
 The Dispossessed - Ursula Le Guin
 Nineteen Eighty-Four - Orwell
 Blue Mars - Kim Stanley Robinson
 Illegal Alien - Robert Sawyer
 The Dosadi Experiment - Frank Herbert
 High Justice - Jerry Pournelle
 An Exchange of Hostages - Susan Matthews

Military science fiction - war in the future
 Ender’s Game - Orson Scott Card
 On Basilisk Station - David Weber
 Dauntless - Jack Campbell
 Dorsai!- Gordon R. Dickson
 A Hymn before Battle - John Ringo
 Hammer’s Slammers - David Drake
 Starship Troopers - Robert Heinlein
 Old Man’s War - John Scalzi
 The Forever War - Joe Haldeman
 With the Lightnings - David Drake
 Mutineer - Mike Shepherd
 The Warrior’s Apprentice - Lois McMaster Bujold
 Valor’s Choice - Tanya Huff

Exploration and/or living on another planet - classic theme in science fiction
 Have Space Suit Will Travel - Robert Heinlein
 2001 A Space Odyssey - Arthur C. Clarke
 The Martian - Andy Weir
 Mars - Ben Bova
 Red Mars - Kim Stanley Robinson
 Farmer in the Sky - Robert Heinlein
 Binti -Nnedi Okorafor

Hard science fiction - Science-based especially concerning physics
 Revelation Space - Alistair Reynolds
 Leviathan Wakes - James Corey
 Seven Eves - Neal Stephenson
 2001 A Space Odyssey - Arthur C. Clarke
 Children of Time - Adrian Tchaikovsky
 Consider Phlebas - Iain M. Banks
 The Three-Body Problem - Cixin Liu
 Legacy - Greg Bear

Feminist science fiction - examination of feminist themes in alternate universes or the future
 The Female Man - Joanna Russ
 The Handmaid’s Tale - Margaret Atwood
 Native Tongue - Susette Haden Elgin
 The Gate to Women’s Country - Sheri S. Tepper

Technology - longevity, cloning, first true space drive et. The impact of technological changes on society and people
 Leviathan Wakes - James Corey
 Ancillary Justice - Ann Leckie
 Cyteen C. J. Cherryh
 All System’s Red - Martha Wells

Generation ships - early space colonization before a Faster-than-Light drive is invented,
 The Dark Beyond the Stars - Frank M. Robinson
 Hull Zero Three - Greg Bear
 Dust - Elizabeth Bear
 Orphans of the Sky - Robert Heinlein
 An Unkindness of Ghosts - Rivers Solomon

Traders - The need to trade for things doesn't go away in the future
 Quarter Share - Nathan Lowell
 Alliance Rising - C. J. Cherryh
 Trading in Danger - Elizabeth Moon
 Merchanter’s Luck - C. J. Cherryh
 The Pride of Chanur - C. J. Cherryh

Lost colonies - We sent them out then lost track of them
 All the Weyrs of Pern - Anne McCaffrey
 Remnant Population - Elizabeth Moon
 Forty Thousand in Gehenna - C.J.Cherryh
 Off Armageddon Reef - David Weber

Science fiction fantasy - elements of both genres
 The Compleat Enchanter - L. Sprague de Camp
 Dragon Flight - Anne McCaffrey
 The Gunslinger - Steven King
 The Dying Earth - Jack Vance
 Black Sun RIsing - C. S.Friedman
 The Cloud Roads - Martha Wells

Humor - everybody needs a laugh now and then
 The Hitchhikers Guide to the Galaxy - Douglas Adams
 Redshirts - John Scalzi
 Callahan’s Crosstime Saloon - Spider Robinson
 The Adventures of the Stainless Steel Rat - Harry Harrison
 Space Opera by Catherynne Valente
 The Long Way to a Small, Angry Planet - Becky Chambers
 Year Zero: A Novel - Rob Reid

Parallel Universes/Alternate History - Examination of what would change if history changed or how an alternative universe might operate
 1632 - Eric Flint
 The Calculating Stars - Mary Robinette Kowal
 The Once and Future Witches - Alix E. Harrow
 The Crossroads of Time - Andre Norton
 The Man in the High Castle - Phillip K. Dick
 The Practice Effect - David Brin
 Conquistador - S. M. Strling
 The Guns of the South - Harry Turtledove
 Worldwar: In the Balance - Harry Turtledove
 Hells Gate - David Weber, Linda Evans
 Crystal Soldier - Sharon Lee, Steve Miller

Literary - for the more literary minded
 The Sparrow - Mary Doria Russell
 The Handmaid’s Tale - Margaret Atwood
 Kindred - Octavia Butler
 Fahrenheit 451 -Ray Bradbury
 Slaughterhouse-Five - Kurt Vonnegut
 Cloud Atlas - David Mitchell
 The Left Hand of Darkness - Ursula Le Guin

Corporate - Companies exist in the future, too. Sometimes they affect the story
 Little Fuzzy - H. Beam Piper
 Fuzzy Nation - John Scalzi
 Rissa Kerguelen - F. M. Busby
 The Atrocity Archives - Charles Stross
 A Civil Campaign - Lois McMaster Bujold

Robots and androids - who doesn't love robots and androids? Science fiction readers certainly do.
 I, Robot - Isaac Azimov
 All Systems Red - Martha Wells
 The Windup Girl - Paolo Bacigalupi
 Ancillary Justice - Ann Leckie
 Saturn’s Children - Charles Stross
 The Hitchhikers Guide to the Galaxy - Douglas Adams

Clerical/Religious - there is religion in the future and sometimes a conflict of religions from different species
 The Sparrow - Mary Doria Russell
 A Canticle for Leibowitz - Walter M. Miller, Jr.
 The Nine Billion Names of God - Arthur C. Clark
 Calculating God - Robert Sawyer
 The Chaplain’s War - Brad R. Torgerson

Coming of age - young people still grow up and their coming of age stories are always fun
 Citizen of the Galaxy - Robert Heinlein
 Quarter Share - Nathan Lowell
 Space Cadet - Robert Heinlein
 Tunnel in the Sky - Robert Heinlein
 Binti - NnediOkorafor
 The Hunger Games - Suzanne Collins
 Midnight Robber - Nalo Hopkinson
 Ender’s Game - Orson Scott Card

Microbiology, Biology, Genetic Engineering - subset of Hard Science fiction (which many consider the province of physics) based on the biological sciences
 Fantastic Voyage - Isaac Azimov
 Vitals - Greg Bear
 Cyteen - C. J. Cherryh
 The Andromeda Strain - Micheal Crichton
 The Stand - Steven King
 Beggars in Spain - Nancy Kress
 The Atlantis Gene - A. G. Riddle
 Falling Free - Lois McMaster Bujold

Space magicians -subset of Space Fantasy specifically dealing with magicians in space
 Starship’s Mage - Glynn Stewart
 The Price of the Stars - Debra Doyle
 The Witches of Karres - James H. Schmitz
 The Compleat Enchanter - L. Sprague de Camp

Character-Driven - Characters you will never forget. I list the character, then what book or series he/she/it is associated with, then the author. Note the listed character is not necessarily in every book in the series.
 Ari Emory II - Cyteen - C. J. Cherryh
 Honor Harrington - The Honor Harrington Series - David Weber
 Miles Vokosigan - The Vokosigan Saga - Lois McMaster Bujold
 Ishmael Wang- The Golden Age of the Solar Clipper series - Nathan Lowell
 Murderbot - the Murderbot series - Martha Wells
 Ender Wiggin - The Ender’s Game series
 Cletus Graeme - Childe Cycle - Gordon R. Dickson
 Andrei Koscuisko - The Jurisdiction series - Susan Matthews (Note: Andrei is a very flawed character, he is a torturer and a doctor. This series is often searing.)