Stranger in a Strange Land, first published in 1961, was read by many, many people who did not usually read science fiction. It won a Hugo, and introduced the word grok to the '60s.
Here is an ad-free list of novels that won Hugo awards.
2006 Spin by Robert Charles Wilson
2005 Jonathan Strange and Mr. Norrell by Susanna Clarke
2004 Paladin of Souls by Lois McMaster Bujold
2003 Hominids by Robert J. Sawyer
2002 American Gods by Neil Gaiman
2001 Harry Potter and The Goblet of Fire by J. K. Rowling
2000 A Deepness in the Sky by Vernor Vinge
1999 To Say Nothing of the Dog: Or How We Found the Bishop's Bird Stump At Last by Connie Willis
1998 Forever Peace by Joe Haldeman
1997 Blue Mars by Kim Stanley Robinson
1996 The Diamond Age: Or, a Young Lady's Illustrated Primer by Neal Stephenson
1995 Mirror Dance by Lois Mcmaster Bujold
1994 Green Mars by Kim Stanley Robinson
1993 A Fire Upon the Deep by Vernor Vinge; Doomsday Book by Connie Willis
1992 Barrayar by Lois McMaster Bujold
1991 The Vor Game: The Continuing Adventures of Miles Vorkosigan by Lois McMaster Bujold
1990 Hyperion by Dan Simmons
1989 Cyteen by C. J. Cherryh
1988 The Uplift War by David Brin
1987 Speaker for the Dead by Orson Scott Card
1986 Ender's Game by Orson Scott Card
1985 Neuromancer by William Gibson
1984 Startide Rising by David Brin
1983 Foundation's Edge by Isaac Asimov
1982 Downbelow Station by C. J. Cherryh
1981 The Snow Queen by Joan D. Vinge
1980 The Fountains of Paradise by Arthur Charles Clarke
1979 Dreamsnake by Vonda N. Mcintyre
1978 Gateway by Frederik Pohl
1977 Where Late the Sweet Birds Sang by Kate Wilhelm
1976 The Forever War by Joe Haldeman
1975 The Dispossessed: An Ambiguous Utopia by Ursula Le Guin
1974 Rendezvous With Rama by Arthur Charles Clarke
1973 The Gods Themselves by Isaac Asimov
1972 To Your Scattered Bodies by Philip Jose Farmer
1971 Ringworld by Larry Niven
1970 The Left Hand of Darkness by Ursula Le Guin
1969 Stand on Zanzibar by John Brunner
1968 Lord of Light by Roger Zelazny
1967 The Moon Is a Harsh Mistress by Robert A. Heinlein
1966 Dune by Frank Herbert; This Immortal by Roger Zelazny
1965 The Wanderer by Fritz Leiber
1964 Way Station by Clifford D. Simak
1963 The Man in the High Castle by Philip K. Dick
1962 Stranger in a Strange Land by Robert A. Heinlein
1961 A Canticle for Leibowitz by Walter M. Miller
1960 Starship Troopers by Robert A. Heinlein
1959 A Case of Conscience by James Blish
1958 The Big Time by Fritz Leiber
1957 -
1956 Double Star by Robert A Heinlein
1955 They'd Rather Be Right by Frank Riley
1954 -
1953 The Demolished Man by Alfred Bester
Hugo awards by catagory, but this list is not up-to-date.