"Roadside Picnic" author Boris Strugatsky died in Russia at age 79 on Monday.
The prominent science fiction writer died in a St. Petersburg hospital after suffering from a grave illness, according to reports.
Between the 1960s and 1980s, Strugatsky collaborated with his late brother, Arkady, on over a dozen books. Their books covered philosophy, space travel, and satiric works on the Soviet system. They were printed in 321 editions in 27 countries.
Perhaps best known for their book "Roadside Picnic," the brother duo broke apart with the death of Arkady in 1991.
"Roadside Picnic" was made into an acclaimed film entitled "Stalker" and directed by Andrei Tarkovsky.
Following his brother's death, Strugatsky continued working and published two novels on his own. While not widely read, the works were known for their political content as well as the author's critiques of President Vladimir Putin.
Regardless of his writing, Putin called Strugatsky "one of the brightest, most talented and popular writers of the [past and present] time" in a telegram sent to the writer's relatives, reported The Moscow Times.
The Russian president added that Strugatsky was the "ruler of the dreams of many generations," according to his telegram.
On Twitter, many of Strugatsky's fans are mourning the writer's death on Tuesday.
"Boris Strugatsky has passed away," wrote Dmitry. "A great writer and thinker. An irreplaceable loss to Russian and world literature."
"Rest in Peace, Boris Strugatsky," posted Gunther. "Your brother and you will always be in my list of top favorite sf authors."
Stephen wrote, "I just heard that Boris Strugatsky died. If you're into SF and that name means nothing to you, you're not into SF."
"Goodbye, Boris Strugatsky," posted Martin. "You are and will always be my favourite science-fiction authors."
Steven added, "RIP, great science fiction writer."