I’m trying to recall. In the Asimov’s Foundation series was a there reveal near the end that human protecting robots secretly killed everything in the galaxy that they thought might have competed with, or threatened, human beings?
I don’t think Daneel et al. actually killed off aliens-- It’s implied that, through time-travel shenanigans, that they prevented them from ever arising to begin with. Except that they didn’t really succeed, as evidenced by the Solarians, who regardless of their origins are aliens in any meaningful sense.
I haven’t read any of the post-Asimov books, but in Foundation and Earth, it seems from R. Daneel Olivaw’s reactions to Golan Trevize’s “Zeroth Principal of Psychohistory” that no non-human (or human-derived) intelligences have ever been encountered by humans or human-created robots. The Solarians are indeed implied to be aliens for all intents and purposes, but were not thought of as such before the conclusion of that book.
It is apparently something of an attempt to link the Foundation series and The End of Eternity, I believe.
You asked this question before, I think Re Asimov's "Foundation-Empire" series was Daneel was killing alien civilizations to protect man? - Cafe Society - Straight Dope Message Board
As I wrote then: "In the authorized sequels by Brin, Benford and Bear, the robots spread through the galaxy ahead of the colonizing humans, destroying alien civilizations, and leaving planets ready for cultivation. The humans were manipulated by the robots such that no one thought much about the fact then whenever they got to a planet, they found that it was unoccupied, but ready for occupation. "
I tried to read the Brin, Benford, and Bear sequels, but couldn’t work my way through them. To me, it was too obvious the authors had too much of a thing for, um, Voltaire(?) and Joan of Arc. The stories were just too convoluted for me to follow. They did fill in a couple of blanks, though.
To be honest, the only one of the three I really liked was the Brin - Benford and Bear brought in too much of their own hobbyhorses (one of them used a previously written story, as I recall, with Seldon substituted in for the original protagonist), but Brin either had hobbyhorses that fit with Asimov’s or could fake it well.
This thread might also interest you: Asimov's "Foundation" Being developed for HBO - Cafe Society - Straight Dope Message Board