CS Lewis' angelic "Heaven"-dwelling eldila with the space-dwelling beings in works by Fred Hoyle, James Blish and Poul Anderson. These three hard sf writers present scientific rationales for their imagined extra-planetary intelligences.
Hoyle's Black Cloud, addressing human scientists, says:
"'...conventional religion, as many humans accept it, is illogical in its attempt to conceive of entities lying outside the Universe. Since the Universe comprises everything, it is evident that nothing can lie outside it. The idea of a "god" creating the Universe is a mechanistic absurdity clearly derived from the making of machines by men. I take it we are in agreement about all this.'"
-Fred Hoyle, The Black Cloud (Harmondsworth, Middlesex, 1965), p. 203.
I am in agreement now although not when I first read the book fifty years ago because I had been religiously indoctrinated. Hoyle through his characters, both human and non-human, addresses several important issues:
the role of scientists in society;
the relationship of science to reality;
how intelligence evolved on Earth;
whether there is a larger-scale intelligence;
why the laws of physics are as they are;
whether a larger-scale intelligence might explain the laws of physics.
(Hoyle's latter non-fiction included The Intelligent Universe and he argued against Darwinism.)
The novel is set in the 1960's, thus has become what I call a "past future," but it retains an element of futurity because its closing fictitious correspondence is dated 2021 and ends:
"Do we want to remain big people in a tiny world or to become a little people in a vaster world? This is the ultimate climax towards which I have directed my narrative." (p. 219)
So how do we in 2014 answer that question?