My favorite opening lines that I didn’t see yet are:

Kafka’s “Metamorphosis”

“When Gregor Samsa awoke one morning from troubled dreams, he found himself changed into a monstrous cockroach in his bed”

Tolstoy’s “Anna Karenina”

“Happy families are all alike; every unhappy family is unhappy in its own way.”

And, Gibson’s “Neuromancer”

“The sky above the port was the color of television, tuned to a dead channel.”