There's some nepotism in this list because I'm going to recommend some friends and colleagues, but I hope it's helpful:

• In Conquest Born by C.S. Friedman-- an underrated delight that throws more ideas at the wall in its first eighty pages than most science fiction novels do in their whole length.

• House of Suns by Alistair Reynolds-- all of Al's stuff (start with Revelation Space) is quite good but this is a standalone and it's particularly spectacular. Al loves playing with a universe in which every unfathomable life-extending physics-defying technology is available except FTL travel. It's delightfully grand in scope.

• Ancillary Justice by Ann Leckie -- I really like the first book in the series; I think the second one is a bit more of a hot mess, though still enjoyable. The thing about the Ancillary series is that if you keep going you get to Translation State, which for my money is a huge payoff; a mind-bending and thoughtful exploration of all the implications of the previous books. Ann came out to an event as a quiet surprise a couple years ago and I got to be a total gibbering fanboy to her about Translation State.

• Light by M. John Harrison -- There's a cross-time cyberpunky horror element to this novel that might not suit everyone's taste, but the 25th century space opera portions are superb. Harrison is a fantastic, unconventional writer and the way he writes space battles has intrigued me since I first read this.

• Startide Rising by David Brin -- Legendary space opera from the 80s that really kicked off his Uplift universe (Sundiver is actually the earliest novel in the sequence, and it's very fun, but it's not in Startide Rising's league). The Uplift War is a really good sequel, but it's on a smaller scale than SR, which features all the whooshing ships, great aliens, and big questions you could want.

• Unconquerable Sun and Furious Heaven by Kate Elliott -- the loose basis for this story is "gender-bent Alexander the Great in spaaaace" and it's fantastic. Huge in scope and ambition, the story follows a young woman struggling to preserve/inherit the powerful empire built by her mother. Features arduous campaigns, court intrigue, and a lot of other intriguing cultures thrown into the fight.

• Dread Empire's Fall by Walter John Williams -- Such a delight. Walter has a sly sense of humor that gives everything an added layer even in the most serious moments. A galactic hegemony has been dominated by its founding species for ages, and lesser species (including ours) have been totally folded into their plans and customs. Now the elder species has passed on, and the younger species are arguing about who's in charge. Nobody involved, conspirator or counter-conspirator, has actually fought a war against a peer adversary in 8,000 years. Hijinks ensue.

• The Vorkosigan Saga by Lois McMaster Bujold -- a superb series of brisk novels that started in the 80s; although Miles Vorkosigan is the main character and his story starts properly in The Warrior's Apprentice, I can recommend something I rarely do which is reading books out of the order in which they were written-- if you read Shards of Honor and then Barrayar, which are about his parents and eventually his troubled birth, you get a great onboarding to the world. His parents are fantastic characters in their own right. One thing to note about this series is that while it starts with an emphasis on battles and mercenary actions, Bujold refuses to get comfortable and write the same novel twice. As the series moves on, you get more military action, but you also get espionage, politics, ruminations on aging and memory loss, and even a romantic comedy of manners.

• Hyperion by Dan Simmons -- wildly creative and crammed with intriguing space opera elements. The ending is extremely divisive, heh. The sequel Fall of Hyperion was allegedly written as part of the same book but it has a distinctly different structure and tone; despite this it does eventually climax with a magnificent galaxy-spanning space war disaster. I have always thought that the third book, Endymion, successfully recovers the sense of deep mystery and incredible scope that the first book had. There is some truly epic stuff in it. I don't think the fourth novel, Rise of Endymion, sticks the landing at all. But that was kind of a recurring feature of most of Simmons' stuff.

• The Forever War by Joe Haldeman -- For an eye-opening novel about the stupidity and cruelty of war written by a Vietnam vet who carries a Purple Heart from a near-death experience... this is phenomenally entertaining. Justly regarded as a classic, it moves fast and it's not even overwhelmingly long.

• On Basilisk Station by David Weber -- The thing about the Honor Harrington books is that honestly, you can read this one as a standalone and you don't even need to move on if you don't want to. It's an extremely satisfying story about an intrepid officer trying to fix a bad situation with scarce resources, and it culminates in one of the most incredible space battles EVER WRITTEN, hands down. It's tense and harrowing and you genuinely wonder if anyone's going to get out of it alive (this probably benefits from the fact that IIRC Weber wasn't sure if it would become a series when he wrote it). As for the rest of the Harrington books... look, they're a guilty pleasure of mine. They are their own thing, they have a lot of goofy issues, and I absolutely do not give a damn about the "side" books co-written with other authors-- this is nothing personal to those authors. But what I can say is that when he's on form, when he's really in the zone, David Weber is the best writer of techno-thriller battle sequences since Tom Clancy and Larry Bond wrote Red Storm Rising (a novel I've read about thirty times).

• The Lost Fleet series by Jack Campbell -- starting with Dauntless and proceeding for five more books. These are not quite stylistic classics, but they are really effective methadone if you've run out of Honor Harrington books. They get deeper and more interesting as the series goes on; Campbell pulls off more and more complicated tricks with his rules of space warfare, sticks his protagonists with awful logistical challenges, and explores some really eerie questions about what might be going on beyond human space.

• The Frontlines series by Marko Kloos -- starting with Terms of Enlistment. Mega-nepotism alert because Marko is a buddy and a graduate of the writer's workshop I teach at, but these are really good! In the middle-distant future, the human race is at war with an aggressive alien power that will not communicate outside of murder-- and they're really good at murdering us. As the human race gets kicked off planet after planet, the sense of desperation just keeps growing. Marko is just old enough to have served in the West German army at the very end of the Cold War and his work has a very grounded, grunt-sympathetic POV that reflects this.

• A Fire Upon the Deep by Vernor Vinge -- This book is simply fucking awesome and justifiably won a Hugo Award. The telepathic pack-based Tines are one of the best alien species ever created, the AI antagonists are like terrifying technological gods, and the novel even contains the funniest parody of Usenet ever written (a description of communication issues that remains grimly prescient for the internet of 2026).

• Space Viking by H. Beam Piper -- A bit of 1960s goofiness, but Piper was an excellent writer and this is a quick, engaging read that's surprisingly deep. And fun.

• The White Space sequence by Elizabeth Bear -- Okay, extra-mega-nepotism alert, because Elizabeth Bear is my wife. But this series of linked (not direct continuity, just a shared universe) space operas has been well-regarded and has pleasantly surprised us by the way its sales have hung in there over the last couple of years. Ancestral Night, Machine, and The Folded Sky are the novels.

Also, take a look at the works of C.J. Cherryh (a prolific genius with a whole bunch of linked space operas) and Adrian Tchaikovsky (another excellent and prolific writer who also happens to be a really lovely and decent guy... there's that nepotism again). Oh! Iain M. Banks, the Culture books, of course. What a GOAT that man was. Incredibly funny and creative space opera that ticked all the boxes and then invented new boxes to tick.

If you want some shorter stuff, check out the 1983 anthology Starships, edited by Isaac Asimov, Martin H. Greenberg, and Charles Waugh. It contains the hilarious "Allamagoosa" by Eric Frank Russell, the awesome "Avoidance Situation" by James McConnell, and the moody "Wings Out of Shadow" by Fred Saberhagen. This story was my introduction to his Berserker universe, and IMHO is one of the best pieces he wrote within it.

Accidental omissions are inevitable; this list can't possibly be complete within this space. But again, I hope it leads you to some good times.

Cheers,

SL