It is unfair to say that because Herbert portrayed one gay character negatively that he was homophobic. This is from "God Emperor of Dune:" "It's perfectly normal for adolescent females and males to have feelings of physical attraction to their own sex...it's part of our heritage... I will tell you this only once. Homosexuals have been among the best warriors in our history, the berserkers of last resort. They were among our best priests and priestesses. Celibacy was no accident in religions. It is also no accident that adolescents make the best soldiers." This was in the context of one character (Moneo Atreides) addressing another (ghola-Duncan Idaho) who was 3500 years behind in evolution, and had a problem with seeing two women kiss. So it's no mystery which viewpoint Herbert thought was more advanced. And this was in a book published in 1981, before the aspects of history it touched on were well known, so you could say that on this, as on many other issues, he was ahead of his time.
The preceding is the original text of this writeup, my first ever, and is a response to Anacreon's writeup. What follows is an attempt to provide a more complete biography.

Science fiction is mainstream. Everything else is kind of an attendant time-bound piece of science fiction.

In 1980, Frank and Beverly moved to Maui. In 1984, Ann died, and Herbert wrote for her a moving eulogy that was included in the introduction to Chapterhouse: Dune. In 1985 he was diagnosed with pancreatic cancer and underwent experimental treatment at the University of Wisconsin. He died on February 11, 1986, at the age of 65.