The Culture/Consider Phlebas

The first Iain M Banks novel set in The Culture, it concerns the war between the Culture and the Idiran civilization, an event whose reprecussions affect all of the future novels in the series. Interestingly, the novel is mostly told from the perspective of Bora Horza Gobuchul, a "Changer", who sides with the Idirans and sees pretty much all of the Culture's signature aspects in a highly negative light.

Tropes used in The Culture/Consider Phlebas include:

All for Nothing: Every damn escapade Horza gets his team involved in ends in disaster. Yet still he won't quit while he's behind.
Anti-Hero / Anti-Villain: Horza is the former in respect to the novel, but could be seen as the latter to the extent that the Culture itself is the protagonist of the series.
Backwards Name: (Bora) Horza gives Orab as a false name at one point.
Brick Joke: the Megaships.
Chase Fight
Cluster F-Bomb: Lamm.
Death World: An unseen example is the Idirian homeworld, which has caused them to evolve into Badass warriors. The planet where the lost Mind is hiding is something of a literal example, being a world that once evolved sentient life with an advanced civilization until said life wiped itself out in the culmination of something like our Cold War.
Dead Person Impersonation: At the opening of the novel, Horza has been exposed impersonating a politician for the Idirans; once he's picked up by Space Pirates, he makes plans early on to replace the Captain, and eventually does.
Inside a Computer System/Cuckoo Nest: Horza is knocked out and dreams that he's woken from an immersive computer game. The technician tending to him gets some of the details of his story wrong, and when Horza tells him so, the guy realises he's woken up the wrong person and puts him back under. Horza wakes up, and none of this is ever mentioned again.
Downer Ending
Fantastic Racism: Horza hates and despises sentient machines (to be sure, he doesn't believe they're really sentient). Most Idirans despise non-Idirans (see Superior Species), and they have a religious justification for it.
Fat Bastard: The Prophet of the Eaters. Yuck.
Hero Antagonist: Balveda.
Non-Action Snarker: Jandraligeli.
Proud Warrior Race Guy: The Idirans hold firm religious beliefs in fighting to the death. For example:
- Xoxarle, who—after Horza and company capture following a Ray Gun fight—spews insults at the Changer in a futile attempt to get himself killed and reunite with his fallen comrades, rather than face the shame of being taken prisoner.
- Quayanorl, Xoxarle's comrade, despite grievous damage done to him during the aforementioned lasergun fight, manages to drag himself up to the train parked in the station, get it running, and wham it into the train sitting in the station Horza and the others are occupying, kicking off the cataclysmic fight that gets everybody but Balveda and Unaha-Closp killed. The Idiran fulfills his wish to die having contributed an noble to his species' cause.
Ragtag Bunch of Misfits: the Space Pirates - things don't go well for them
Rock Beats Laser: Armed with laser weapons, the Space Pirates attack an old temple located in a non-spacefaring civilization, defended only by monks with primitive firearms. See Temple of Doom below. About half the company is wiped out in the resulting chaos.
Scary Dogmatic Aliens: The Idirans.
Shapeshifter Identity Crisis: Horza (as a shapeshifter) has a literal invocation of this trop. He doesn't lose control of his shifting, but several of the dream sequences he experiences hint that he may not actually be who he thinks is
Snarky Non-Human Sidekick: Unaha-Closp. Throughout his tenure with Horza he becomes the Butt Monkey of the gang, being ordered about to perform the dirty work (perhaps due to his high practical utility as a Culture drone). Despite his cynical attitude towards Horza's endeavors, near the end he prevents Balveda and Horza from being mauled to death by Xoxarle.
Space Pirates: Kraiklyn's Free Company.
Sympathetic POV: Horza hates the Culture and, for example, while the later novels draw humor from the humorous/macabre names the Culture gives to ships, he's disgusted by this apparent display of the Culture's cavalier attitude towards something as grim as interstellar warfare.
Superior Species: Thanks to evolving on a Death World, Idirans are practically immortal and indestructible; also, the Changers' shape-shifting and poison claws are definitely a product of some intricate genetic engineering. In the end they are utterly crushed by the Culture: the Space Hippies might seem to be hopelessly outgunned by the Idirans at the beginning of the novel, but that's only because they have not even started to fight back yet. Being physically superior than pan-humanity as individuals just doesn't go that far in a high-tech galactic war. Especially when they have A Is running the show with brains so large they have to use Hyperspace for data storage. This is actually why Horza sides against the Culture, he doesn't trust the machine minds, and sees them as a threat to the galaxy as a whole. He thinks the Idirans are pretty damn superior, but still just another empire like all the others from history
Temple of Doom: The Temple of Light; it's constructed from crystal blocks that turn shots from laser weapons back on the shooter, among other tricky defenses.
This Was His True Form: Balveda has a moment invoking this trope as she takes Horza's corpse with her off the planet at the end, reminiscing that for all their interactions, this is the first time she has seen his real face.
What Measure Is a Non-Cute? / What Measure Is a Non-Human?: The Idirans possibly appeal less to the reader being of terrifying and nonhumanoid appearance. Homomda, who at the time were a shade ahead of even the Culture, had assisted the Idirans in the past at least partly because of their shared tripedal ancestry, and even supported them for a time during the Culture-Idiran War. Once you really get to know the Idirans things don't improve over the first impressions.
- Unaha-Closp plays a vital role at the end of the novel, contrary to Horza's implicit discrimination against the drone.
Worthy Opponent: Horza and Special Circumstances agent Perosteck Balveda to each other.
- Horza reminisces that they've both been in situations where one was about to die and the other didn't help, but when push comes to shove they're not keen on actually killing each other.
Zero G Spot