There are hundreds of novels about the apocalypse, here are just a few that I have enjoyed...
(1958) by Brian Aldiss. Aftermath of collapse of society in a generation star-ship. You might also try Greybeard
(1964), a story of a future where everyone is sterile and the youngest couple left in the world are in their 50's, or Hothouse
(1967) a story set after the virtual exinction of humanity where the survivors compete (poorly) with other animals in a world-girdling jungle.
A Canticle for Leibowitz
(1959) by Walter M Miller (won the Hugo) a story of rebuilding civilization after nuclear war.
The Forge of God
(1987) by Greg Bear, an end-of-the-world story - don't trust aliens (it also has a sequel, Anvil of Stars
Wolf and Iron
(1990) by Gordon R Dickson, a detailed and gritty story of survival after society collapses in the USA.
Death of Grass
(1956) by John Christopher, a plague has wiped out all grasses and cereals. Civilization is proved to be a thin veneer when people must fight to secure what little food remains.
Day of the Triffids
(1951) by John Wyndham, when the population of the world is blinded, genetically-engineered mobile plants find themselves accidently in the ascendency.
(1955) by John Wyndham, in an agrarian world recovering from nuclear war, mutant children try to hide their telepathic powers from a society that will kill them without mercy - a hint of Salem perhaps?
(1964) by Robert Heinlein, an American family are catapulted into a post-nuclear society that highlights the assumptions and prejudices of 1950's America by inverting them.
(1980) by Russell Hoban, 2000 years after the apocalypse in England. A strange anarchical society that lives in the ruins. The whole book is written in a dialect out of which the reader can pick the twisted remnants of concepts from our own time.
(1961) by Daniel F Galouye, post-apocalypse, people live underground in a medieval society. The most striking thing is that there is no light, people use their enhanced sense of hearing to echo-locate and the very concept of vision has been forgotten. But then outsiders break into the underground world...
(1991) by Vernor Vinge, a story that goes from the near future when the world-changing discovery of how to create stasis-fields is made, through apocalypse and on into the far future where a few survivors use their stasis-fields to skip through millions of years while they try to recreate humanity.