Ah heck, I'll just toss it up and see what happens.
Name: N/A, dubbed 'The Satyrs'
Appearance: The beasts could almost pass for the mythical Satyrs, and in fact are what those myths were based off of. Picture a cross between a goat and a neanderthal and make it about 8 feet tall and you're on the right track. Furry allover with goat horns and legs, the facial and bodily structure is strongly reminiscent of human but not quite there.
Personality: Savage. Like a wild animal, if one that is more cunning then most. Not intelligent, it doesn't read or write- but it can figure out puzzles and solve problems surprisingly quickly.
Current Clothing: None
Oviposition: No
Pregnancy: Yes, and the zygotes implant so well that it's believed that it's impossible to abort a hybrid offspring without surgically removing part of the mother's womb.
Copious amounts of cum: Yes, though threw comparatively normal human anatomy.
Pheromones/Aphrodisiac: Yes, but relatively weak. Causes sexual arousal and encourages feelings of submittance, subservance, and docility.
Bio: Technically not an Alien, the 'Satyrs' actually evolved from Earth alongside the human race. Homo Satyrisis as a rule would be more powerful a creature individually, but Homo Sapians took to group tactics better and had some level of division of labor between the sexes where as Homo Satyrisis was overwhelmingly dominated by male social structures. As a result while Homo Satyrisis would usually beat a Homo Sapians one-on-one, as a species Homo Sapians was winning.
Toward the end of Homo Satyrisis as a species, they did evolve some interesting treats. The two species were always close enough that interbreeding would produce hybrids but Homo Satyrisis started making adaptations to use this as a successful breeding strategy- like a pheromone production so that when a male Homo Satyrisis decided to rape a female Homo Sapians they wouldn't fight back (as hard) and be sexually receptive to it.
What really got those original alien zoologists interested though was a hormone they discovered in the semen of Homo Satyrisis. Their own species had no problem completing the breeding act but the radiation of space travel from their engines left them with a very high miscarriage rate. This hormone encouraged the zygotes of Homo Satyrisis matings to implant, and did it so well that abortions are almost impossible without surgically removing a portion of the womb.
So to save their own species, the alien zoologists abducted a few Homo Satyrisis and began harvesting this hormone- something that cut their miscarriage rate in half overnight and saved their own kind. The current 'Satyrs' are the descendents of the originals, whom the aliens continue to farm for this miracle semen hormone to improve their own birthrates. Unfortunately, since they were unable to capture any female Homo Satyrisis before they went extinct in the wild the only way to breed more Satyrs without risking cloning related issues is to breed them with humans- and so far there have been no recorded fertile female hybrids and only about one in a hundred male hybrid offspring genetically lines up right to be a fertile Homo Satyrisis.
And it turns out they're just fine with hundreds of human women being raped repeatedly and thousands of human-satyr hybrid bastard offspring if it means one more source of this precious anti-miscarriage hormone. . .