Robert Silverberg ("Silverbob" to his friendsnote often spelled "AgBob"—"Ag" is the chemical symbol for silver) is an enormously prolific science fiction and fantasy writer, and winner of multiple Hugo and Nebula Awards.Starting his career in the 1950s, Silverberg was an instant hit, earning a special Hugo for Best New Writer. During this period, he used several pen-names, including David Osborne and Calvin M. Knox, as well as his own name. He also regularly collaborated with Randall Garrett; the two usually published as "Robert Randall".It was in the sixties, though, that Silverberg really found his voice. The "New Wave" movement was pushing science fiction toward more literary experimentation, and Silverberg, though never actually a part of that movement, was inspired to write more complex and mature works that opened up new audiences for him. Some of his works from this period, including the novels To Live Again, The World Inside, and Dying Inside, as well as the award-winning novella "Nightwings", are still considered among his best.After briefly retiring in the mid-seventies for health and personal reasons, Silverberg returned in 1980 with his smash hit, Lord Valentine's Castle, the first book of the Majipoor Series, which now has over half a dozen novels and many short stories. He continues to write a wide variety of SF. In 2004, he was named a SFWA Grand Master.His short story "To See The Invisible Man" was adapted for a 1980s episode of The Twilight Zone.
Allohistorical Allusion: "A Hero of the Empire" has the Roman main character speculating what the world would be like if he doesn't assassinate Mohammed before Islam takes off. He does.
Alternate History: He wrote a number of stories in a universe in which Rome never fell, taking place over the course of several thousand years, and collected in a book called Roma Eterna.
Arcology: The 3 km-tall "urban monads" in The World Inside that house 800,000 people each were inspired by Paolo Soleri's earliest elucidations of the concept.
Artificial Human: The misnamed "androids" of Tower of Glass. They're visually distinguished from "normal humans" (whom they call "womb-born", and themselves "vat-born") by red skin and lack of body hair.
Bio-Augmentation: In the story "At the Conglomeroid Cocktail Party", genetic engineering is such a common and casually-regarded thing in the far future that people actually hold "fetus parties" where they invite the guests to come up with the best design for the hosts' future offspring.
Birth-Death Juxtaposition: Enforced out of necessity, due to limited resources, at the beginning of At Winter's End. Almost no one's allowed to conceive a child to begin with; the few who are allowed to procreate are required to wait until someone's committed ritual suicide at the allotted age.
The Black Death: In Up the Line, there is a popular series of time tours tracing the 14th century Black Death epidemic. Protagonist Jud, while a bit depressed, takes one tour in the series of four (it was the one he could get a spot in on short notice).
Blind and the Beast: In "To See the Invisible Man", a man sentenced to a year of "societal" invisibility manages a brief conversation with a blind man, who ends up rejecting him just like everybody else.
Brain in a Jar: in "Nightwings", brain jars effectively serve as information storage systems.
Face of the Waters takes place on an aquatic example. The entire planet is water and a few floating "islands" of coral, inhabited by invincible rammerfish, mouths that can swallow islands whole, orifice-invading eels, and worse. The only actual land is the Face of the Waters, a hunk of bare psychic-radioactive rock that possesses whoever comes near it. The humans face all this with Bronze Age level technology, since there's no metal or trade on the planet.
This trope could have been very easily instead named Planet Of Death, after his 1960 novel. With such wonderful things upon the 'Let me eat you first' carnivorous flora-covered landscape like quicksand-like pits that are actually incredibly intense forms of acid and razor-toothed, flesh-eating birds, this is a place where literally everything that you see has one thought on its mind: it wants to eat you.. After the heavily-armed explorers are wiped out to all but the last two men, they have the following conversation before they get the hell outta there:
Man #1: There's just one more thing. The rules say that we have to give the planet a name before we leave. We haven't done that yet.
Divided States of America: The short story "The Palace at Midnight" is set in The Empire of San Francisco, in a really balkanised USA. One of the characters is the ambassador from the Republic of Monterey; also mentioned are the Holy Carolina Confederation, the Three Kingdoms of New York, the Realm of Wicca in Oregon, and The Grand Duchy of Chicago.
Dystopian Edict: In "To See The Invisible Man", society requires everyone to be friendly and warm to each other at all times. Anyone convicted of being "cold" must spend an entire year with a mark on their forehead that warns everyone else not to acknowledge their existence in any way.
Easy Amnesia: How It Was When The Past Went Away has three drugs that do this, varying in what part of the brain they wipe. A paranoiac dumps all three of them in the water supply of a major city as a way of taking revenge on the world around him, and winds up creating a blissful cult of people who drink to forget all their mistakes and frailties. (This is apparently supposed to be a good thing.)
The Empath: Interesting version in The Man in the Maze. The titular man gains, as a result of a contact with alien race, an inverted version of empathy — he doesn't receive emotions, he constantly projects his own. All of them, down to and including subconscious ones. As it turns out, these deep human emotions are mostly quite unpleasant... As a result, nobody can stay close to him for any length of time (the strength of the psychic barrage is decreasing with distance), and he has to hide in the nigh-inaccessible maze.
Empty Shell: In Recalled to Life, a process is invented that can restore recently dead (i.e. within a day or so) people to life. (It doesn't actually heal whatever killed them, so it's mostly useful for drownings and the like.) One catch: there's about a one-in-six chance of restoring a mindless shell.
Equivalent Exchange: in The Time Hoppers, material objects can only travel to another time by swapping places with an equivalent mass.
Free-Love Future: The World Inside is set in a huge skyscraper (Urban Monad or Urbmon), in which men are expected to go "night walking", wandering into other peoples' homes for sex, and it's unthinkably rude for a woman to refuse an advance. Silverberg goes into a bit of detail as to how such a society would produce unique sexual hangups of its own. One character is trying to make her husband jealous, which he points out is ridiculous. Meanwhile, she mocks him for sleeping with a woman because he's attracted to her brother—instead of sleeping with the brother.
Immortality Seeker: In The Book of Skulls, all four of the protagonists are looking for eternal life. Which ones are the villains and which the heroes for doing so becomes increasingly less clear-cut as the novel progresses.
Intelligent Gerbil: The Nildoror in Downward to the Earth are basically sentient elephants who, for spiritual reasons, become sentient bear/tapir creatures every few years.
I Want My Jetpack: The 1960 book Lost Race of Mars told the story of two preteen siblings whose parents were taking them to Mars to spend an Earth year, starting in the middle of 2017. This story predicted a city, their host city, having been founded in 1991, and a manned spaceship reaching Mars in 1970. Well...
Japan Takes Over the World:Hot Sky At Midnight has a dystopian future where the Earth's climate has been damaged beyond all repair, two Japanese mega-corps have taken over the world economy and are battling for supremacy: Samurai Industries, based out of Tokyo, and Kyocera-Merck, based out of Kyoto. Most workers are stuck in their company, hoping for a job that has "slope" to a better grade (as in, pay grade). Positions within the company hierarchy are highly stratified, with one's level of clearance determined by position; asking questions beyond your grade is bad for your career health. These positions are known as "Salaryman X", with X being a number (a lower number means a higher rank). Interestingly, just having a "Japanese" name, or being part Japanese, does not guarantee any favourable position; only the "purest" and most dedicated are worthy to ascend the ranks.
Mark of Shame: In the short story "To See The Invisible Man", a man is punished for "coldness" by having a mark affixed to his forehead so everyone else will know to shun him.
My Own Grampa: Up the Line has a character who is trying to sleep with all his female ancestors, except his mother (as he puts it, "I draw the line at abominations"). He's careful not to father any children, he is just seeking to cuckold all of his male ancestors (except his father because sleeping with his own mom would be sick).
Naked on Arrival: The Masks of Time begins with a time traveller from a millennium in the future arriving on the Spanish Steps in Rome, stark naked. Played with — the point-of-view character isn't present for the arrival itself and only knows about it through the TV news reports, which include witnesses arguing about exactly how naked he was.
No Ending: Up the Line ends with the hero hiding from the Time Service in an obscure era where with any luck they'll never find him. He knows however that his respite is only temporary, since instead of killing him directly they can cause him to never have existed in the first place, and even as he speculates this, his narration — just as he predicted — is cut off short in mid-sentence.
Non Sequitur Causality: In the short story "Needle In A Timestack", time travel is common for holidays, so minor changes (your car was a grey Toyota, now it's a silver BMW) are just "the little annoyances of modern life". Unless your wife's ex-boyfriend is trying to undo your marriage.
No Transhumanism Allowed: Played in a minor note in The Great Conglomeroid Cocktail Party. Transhumanism itself isn't necessarily bad—what's bad is when those who have modified themselves start to look down on (and exploit) everyone else.
One Steve Limit: In The Alien Years, a rugged retired colonel named Anson founds a self-sustaining community of rugged survivors on his ranch near LA. Many of his descendants are named Anson, making it hard to tell them apart. (It doesn't help that they all have the same role in their community, and all act the same.)
Parental Incest: In Up the Line, one of the Couriers, who has some major father issues, has a goal to sleep with every female ancestor he has, as a gesture of contempt toward their mates. (Although he does skip his actual mother: "I draw the line at abominations".)
Plagiarism In Fiction: The protagonist of Dying Inside makes his (not very good) living by selling plagiarized papers to college students.
Population Control: Inverted in The World Inside. In the year 2381, most of Earth's 75 billion people live in three-kilometer-high (9,000 feet) "urban monads", where they start their large families around puberty. One man has four children. It is considered shamefully low, but his wife is infertile due to an accident during surgery. He is considering taking another.
Posthumous Narration: In The Book of Skulls, two of the four narrators are dead by the end of the story, yet they still narrate the events leading up to their death, leaving the reader wondering who it is to whom they were actually talking.
The Quisling: In The Alien Years, a nerdy hacker breaks into the conquering aliens' computer system, but instead of trying to use it against them, he offers them his help in return for power and a harem.
Ragnarok-Proofing: In Across A Billion Years, the protagonist (who is a junior member of a mixed alien archaeological expedition) is off to a dig site containing artifacts of the High Ones, a race that existed over a BILLION years ago, give or take a hundred million years. All the technology found is in perfect working order including a large sphere that proves to be a holographic projector that sends them questing after the lost secrets of these ancient precurser beings. Think about that, the percentile error alone covers a span of geological time greater than the death of the dinosaurs all the way to now and the stuff works perfectly even advanced robots stored on asteroids in the depths of space. Even if something is 100.00 percent proof against rust, corrosion by oxygen, UV radiation, deterioration caused by plants taking root, and inedible, over that time scale you'd expect it to be engulfed in lava or hit by an asteroid.
Reality Show: Foretold in The Pain Peddlers, with a horrid TV show that gives new meaning to the phrase "Operating theater".
Religious Robot: "Good News from the Vatican" is a satirical look at the election of the first robot Pope. Obviously to become Pope he'd have needed to spend years working his way up to cardinal.
Switching P.O.V.: The Book of Skulls has 4 PoVs, all first person. He's said that he found getting the voices right and distinct quite difficult. And it wasn't like he was new in the field at the time!
Thank the Maker: In Tower of Glass, the "androids"note misnamed — they're artificially created biological beings, who tend to refer to themselves as "vat-born", with humans being "womb-born" worship the man who created the process by which they're made. This leads to an all-out rebellion when said creator shatters their faith by fervently denouncing their personhood.
Time Travel for Fun and Profit: In Up the Line, most of the major characters work for the Time Service. The protagonist and several other characters are Couriers, who take parties of tourists to sightsee historical events. One use for the hefty fees charged to the tourists is financing scholarly research via time travel.