The two main ones I can think of are “Dune” and “Foundation”. Any others?
Jack Vance rarely has intelligent aliens, so I’ll nominate “The Demon Princes” series and the “Araminta Station” trilogy.
Also, I can’t recall any intelligent aliens in Heinlein’s “Past Through Tomorrow” series of stories.
It may not be quite what the OP is after, but Red Dwarf has FTL, and no alien intelligent life – in fact, practically no intelligent life of any kind at all.
I’m pretty sure I recall an episode where they were in Starbug and encountered aliens who put them on trial in some manner. Or something. Very hazy recollection.
They pretended not to be humans by putting fake eyeballs on their chins and filming their faces upside down.
“Methuselah’s Children” is part of the Future History series, and it has several alien races.
Jack Vance’s “Planet of Adventure” series has several different alien races on the same planet.
Not aliens. Human-built Simulants. All of the sapient non-humans they’ve met have been somehow created by humans - AIs and holograms, GELFs (Genetically Engineered Life Forms), Cats, Simulants and Mechanoids. And a few other one-off things.
But no aliens, much to Rimmer’s dismay.
Ah, OK. Fair enough!
Dune doesn’t have any aliens? Or are the Fremen simply human emigrants who settled Arrakis eons before any other humans showed up? I forget if Guildmembers were aliens.
The Vorkosiganverse has FTL and no aliens.
I came in here to post several stories, but then I reread that the OP asked for “SF series” and I realized I was only able to come up with the same two off the top of my head. Even series Like Ian Bank’s Culture series and Smith’s Lensman series, which deal mainly with humans, have aliens,even if sometimes only in the background somewhere. I’m not familiar enough with all of Heinlein’s Future History stories (which, imho, is only very loosely a series) to state for sure one way or the other.
So, I eagerly await new posts! 
Ah, Heinlein lovers posted as I was slowly typing
The Spice changed them, iirc.
Meh. The best eyewitness in that fiction is a famous liar.
Since I see no restriction in the OP excluding television series, the reimagined Battlestar Galactica has no aliens.
Edward James Olmos told the producers that the first time they sent him a script with aliens in it, they’d have to rewrite it to explain why Adama died off-screen between episodes, because he’d be out the door.
Nope. All humans. The only difference between mainline human and Fremen was the spice. And the guild navigators/steersmen and face dancers and such are genetically manipulated humans. (the guild navigator in the Lynch movie is ridiculously out-book…the navigators were fishlike, yes, but still humanoid.
Heinlein’s Future History has intelligent aliens even in our Solar System (though these were sort of forgotten, in the later-written stories). One of the stories leading up to the whole Nehemiah Scudder thing dealt with the enslavement of Venusians on human-owned plantations. I’m pretty sure there are Martians somewhere in there, too, but I’m not certain.
That’s an odd question (imho) because the Fremen are human… Paul even has kids with Chani.
IIRC, the Fremen were transplanted to Arrakis … pre-Arrakis they lived a pretty idyllic life, were enslaved, and then dumped on Arrakis. I think this is mentioned in the section where Jessica becomes the Reverend Mother - let’s see…
… Still the corridor remained, revealing to Jessica that the Fremen culture was far older than she had suspected.
There had been Fremen on Poritrin, she saw, a people grown soft with an easy planet, fair game for Imperial raiders to harvest and plant human colonies on Bela Teguese and Salusa Secundus.
Oh, the wailing Jessica sensed in that parting.
Far down the corridor, an image-voice screamed: “They denied us the Hajj!”
Jessica saw the slave cribs on Bela Tegeuse down that inner corridor, saw the weeding out and the selecting that spread men to Rossak and Harmonthep. Scenes of brutal ferocity opened to her like the petals of a terrible flower. And she saw the thread of the past carried b Sayyadina after Sayyadina - first by word of mouth, hidden in the sand chantys, then refined through their own Reverend Mothers with the discovery of the poison drug on Rossack… and now developed to subtle strength on Arrakis in the discover of the Water of Life.
Far down the inner corridor, another voice screamed: “Never to forgive! Never to forget!”
Guildmembers are also human, just so transformed by their spice-rich environment that they must live in tanks super-saturated with spice. I don’t think they really resemble what we saw in Lynch’s movie, however, but I could be wrong.
And “We Also Walk Dogs” seems to imply aliens from Jupiter as I recall (were I collecting the stories for the Future History, I’d exclude WAWD and “The Long Watch” not because they aren’t good stories, but because they don’t fit into the Future History (TLW is clearly a prequel to “Space Cadet” and I can’t see getting the same history containing both the American-dominated Space Patrol and the America of Scudder)
I’ll agree that “We Also Walk Dogs” isn’t actually part of the Future History, which is why I didn’t mention the aliens in it, but I’m not sure about “The Long Watch”/Space Cadet– I think that there’s enough room in the timeline for Scudder to have been before, after, or between those stories.
If we’re including TV, Firefly, of course.