5. The Trial, Franz Kafka (1925)
"Someone must have slandered Josef K., for one morning, without having done anything truly wrong, he was arrested." The eponymous trial of Kafka's 1925 novel concerns Josef K., but even after his arrest he has no idea what he's being tried for. Little clarity is provided along the way, but that's beside the point. The entire novel is contained within the opening sentence - the plot, yes, but also the crucial elements of Josef K.'s character. He is far from an angel, having done several things that one might in fact deem "wrong", but his first instinct time and again as the novel progresses is to blame others for his predicament.
4. Anna Karenina, Leo Tolstoy (1877)
"Happy families are all alike; every unhappy family is unhappy in its own way." Tolstoy produced his fair share of quotable tidbits about love and family. The first line of his 1877 novel Anna Karenina - which, if you're looking for a Tolstoy epic to read, I recommend you opt for over War and Peace - is relevant and at home in any setting or society at any time. It recalls the famous saying "Be kind, for everyone you meet is fighting a battle," a quote which has been attributed to numerous sources over the years, by highlighting how few things exist that will make anyone happy, and how many things exist that will cause pain to someone in the world. These are themes that Tolstoy digs much deeper into as the novel progresses, but his first line encompasses and foreshadows everything to come.
3. 1984, George Orwell (1949)
"It was a bright cold day in April, and the clocks were striking thirteen." At first glance, this sentence is a typical, unexciting opener. It establishes the weather, the month, the time of day, the usual. But April isn't normally a cold month, and unless you're in the military you probably tend to refer to the thirteenth hour of the day as "one o'clock". Thirteen, being the unluckiest number, heralds something amiss despite the veil of normalcy. This is the heart of 1984 - things seem familiar, but it takes very little to penetrate the surface and discover something strange.