The Howard Families are a fictional group created by the author Robert Heinlein.

According to Heinlein, the Howard Foundation was started in the 1800's by Ira Howard for the purpose of selectively breeding human beings to expand their lifespans. (Ira Howard himself did not live to see the outcome; he simply endowed the experiment with his own fortune when he found himself dying of old age in his forties.) The novel Methuselah's Children is focused on the Howard Families, and their quest for acceptance on Earth and other planets.

According to Methuselah's Children, envy of the Howards eventually leads the "short-lifers" to develop a therapy for "rejuvenation." Initially the therapy consists simply of blood replacement (using new blood grown in vitro), but according to Time Enough for Love, this single therapy was eventually expanded to include a number of other associated techniques. Members of the Howard Families generally opt to undergo rejuvenation, thereby extending their already-long lifespans — in practice indefinitely.

The books Time Enough for Love and To Sail Beyond the Sunset tell the stories of two famous Howard Family members; Maureen Johnson and Lazarus Long. Lazarus Long also appears in The Number of the Beast and The Cat Who Walks Through Walls.