I am on a roll with Malignant Narcissists and Sociopaths, so why not go the next step and talk about sadism. It is an uncomfortable topic but hiding behind niceties never helped anyone, so I will jump in. The Mal narc and Sociopath are said to be sadists. I have had experience with the sadism in both of these groups of people, but can’t say if every single person who is a Mal Narc or a Sociopath is sadistic. I can try to find evidence of sadism in the charts, though.
In any topic of this nature, one must start with the moons. The moon is the heart. A man’s heart is his essence. That is my opinion. Hence, we would expect to see a moon that is hardened. I don’t think a person could be sadistic without it. Hence, the moon has to have problems, by sign and aspect. The problems have to be extensive enough to harden them to human suffering. I have seen sadism in a Libra Moon. It was opposed to Chiron. Chiron is a major player in all problematic human conditions. It is the planet which shows our greatest wound. That place is bound to have ramifications. We may turn our pain inward to depression. We may turn it outward to bullying and sadism. Pain has to go someplace. That is as true as any physical law.
Purely by sign, I would say that Libra, Aquarius, Capricorn and Scorpio would be the first to consider in sadism. I think the moon would have to have some afflictions, though. Afflictions are hard aspects such as the opposition and the square. I don’t think any of these moons without afflictions would be sadistic. They may be cold, but sadism is much more than coldness.
The Moons least likely to be sadistic would be Cancer, Aries and Taurus. Cancer is tender. Taurus is kind. Aries is the champion of the underdog. However, if any of these moons are afflicted, you could have sadism.
The Jupiter has to be afflicted to be a sadist. That is my opinion. I have seen Jupiter oppose Uranus in a sadist. I think Uranus and Jupiter in hard aspect would be classic in a sadist. The reason would be that Uranus is out of the box and Jupiter exaggerates what it touches. Uranus can be very detrimental in hard aspect. It is the planet of electrical shock. People with an afflicted Uranus like to shock people. Sadism is a form of shocking because the joy is the surprise. That is a big part of it. Sadists seem to love to prey on the innocent, whether it be children or innocent people. The sadist likes to attack a person when the person least expects it. Sadism loses much of it’s fun if the person sees it coming. Jupiter would have to have very hard aspects to it in order to numb the conscience enough to hurt people.
I want to mention Mars. Sadism is calculated action. Hence, the Mars will probably be go- getter vs a “do nothing” Mars. The quality of your Mars will determine the quality of your drive. your drive will function as aggressive or passive no matter if you are doing something good or bad. I speak about mars in that light, here. Cancer and Pisces Mars are the most impotent. Cancer Mars is passive. He sidles up to a situation, sideways. His hallmark is passive aggression, so he is not likely to lash out in a straight forward way in sadism or anything else. Pisces Mars is too poetic. He is more likely to be lying on his mother’s couch reading poetry than being mean to someone. Pisces does not like to be mean, anyway. The two Mars I would implicate in sadism would be Capricorn,who gets the job done and Scorpio who will pursue a goal to the ends of the earth.
Pluto in hard aspect to Saturn is said to be cruelty. I have not talked to anyone, personally, about this as it is a hard topic to broach and an even harder for someone to admit. It does make sense. Saturn would cool the primal nature of the person. The person would be angry and resentful and could lash out with cruelty. Since I have not seen it in a chart I have done, I will relate it and leave it at that.
The Cardinal Ascendent is thought to be the most capable of cruelty. This is due to the fact that the cardinal sign is more likely to take independent action. The Quadriplicities are cardinal( the leader), Fixed( stubborn) and mutable( anything goes 
) For sadism, one would expect a Cardinal Ascendent. These would be Cancer( cardinal water). Libra( cardinal air), Aries( cardinal fire) or Capricorn(cardinal earth) Would all sadists have a cardinal ascendent? No, but they are more apt to.
House wise, I would think that a 1st house stellium would be the most likely for sadism because this stellium can be the most self centered. If not, one might consider a 12th house stellium because this oen can be the most suppressed. The 12th house is the House of Suppression and this is truly the case. I have seen first hand people with double lives( Pluto in the 12th). In this case, it was truly a case of Superman and Clark kent as one side was sweet as sugar. The other was as wild as Dracula’s daughter. I would be surprised to see this kind of polarized double personality without 12th house planets, but I could be wrong. Uranus in the 12th house is hidden kink. This person may have fetishes that he keeps a secret. This would not be sadism but anything suppressed can come out in strange ways, so I put that here for your consideration. I would not expect sadism from Mars or Moon in the 12th because these planets usually turn their anger inward into depression.
I am picking the brains of my ace Astrology friends on Linda-Goodman.com. They are giving me insights into aspects that I will share with you. People are bringing up a few aspects that I will add to our discussion.
Moon square or oppose Saturn
This would not be a major aspect for sadism, imo. I will tell you why. This aspect would more likely result in depression. The person is more apt to turn depression inward. Moon/Saturn can result in depression because Saturn can make the person’s heart feel rejected and unworthy. Saturn is a harsh planet. When it touches the Moon, one will suffer from self doubt and low self esteem. However, one bright light with Saturn is that time will heal it’s pains if one sticks to basic, sound values such a shard work, responsibility and maturity.
Moon trine Saturn
Some people mentioned this aspect but I think it would provide the opposite effect of sadism. This aspect is grounding and centering and makes for self love and acceptance. I have it at 7 degrees, which is wide, but I can feel it’s beauty when I am upset and need to dig my roots in like a giant oak tree. If you have this aspect, you are blessed. Write to me and tell me what you think if you have this. Sadism is rooted in self hate,as is all bullying. People may not admit this but I think it is true. People who love themselves do not bully. They offer a hand up to those who are in pain.
Moon square or opposed to Pluto
Someone mentioned this but I don’t think this can be linked to sadism. It can be linked to emotional intensity. It can be linked to possessiveness that could result in something like stalking. I say that to give an understanding of the level of intensity that a Moon/Pluto person has. if one wanted to stretch and say that this kind of intensity could result in sadism, I think it would be too great of a stretch, so I cannot add this aspect to our discussion.
To me, to summarize sadism, I would expect a harsh moon, an afflicted Jupiter, a go -getter Mars, perhaps a harsh aspect between Saturn and Pluto and a Cardinal Ascendent.
This is one man’s opinion and experience, so please take it in that vein.