Is there a zodiac sign
of serial killers?

The internet loves assigning a zodiac sign to serial killers. Depending on the post, it's Scorpio — dark, secretive, intense — or sometimes Gemini, Pisces, or Sagittarius. The lists change, but the conclusion stays the same: certain signs are supposedly "more prone to it," "predisposed," or simply more common among violent criminals.

I wanted to start from a more open question: are any zodiac signs actually overrepresented among serial killers? Not just a sign that lands at the top of a ranking, but a sign that appears more often than you'd reasonably expect.

The raw ranking already tells a different story

After cleaning the corpus, Pisces comes out on top with 94 people. Aquarius, Capricorn and Sagittarius follow with 74 people each. Scorpio sits at 65 — not first, but seventh. Gemini closes out the ranking with 56 people.

It's tempting to conclude: "Actually, the serial-killer sign is Pisces." That would be making the exact same mistake with a new winner. A high count only becomes overrepresentation once it's been compared against a relevant expected distribution.

Three claims that keep getting mixed up

1. The descriptive ranking. "In this list, this sign comes first." That's an observation about one particular corpus.
2. Statistical overrepresentation. "This sign appears more often than you'd expect in a comparable population." This claim requires a reference and a test.
3. Individual or causal predisposition. "Belonging to this sign would increase the odds of becoming violent." This is a much stronger claim, and it doesn't automatically follow from the first two.

The jump from the first level to the third is methodologically unjustified. Even if a genuine statistical overrepresentation were detected, it alone would not demonstrate that a sign causes, predicts, or predisposes someone to criminal behavior.

Before counting anything: fifteen fictional characters

The starting corpus was built from Wikidata. It counted 839 entries classified as serial killers. Checking it turned up a very concrete problem: fifteen entries corresponded to fictional or non-human characters. They were explicitly excluded, without silently editing the source file.

Birth dates were then verified, and every calendar variable — year, month, day and sign — was recalculated from the retained date. This step doesn't make the corpus perfect: Wikidata is neither an exhaustive criminological registry nor a universal definition of the term "serial killer." But it does keep the result from resting on duplicates, artificial dates, or fictional characters.

First test: what if every sign were worth one-twelfth?

The first comparison assumes each of the twelve signs should represent exactly one-twelfth of the corpus. That's the simplest hypothesis — and also the most naive.

Put more simply: if you randomly split 824 people across twelve signs, you'd almost never get twelve perfectly equal groups of 68 or 69 people. Some signs would naturally land above average and others below. The test exists precisely to check whether the gaps are too large to be explained by that ordinary variation. Here, they aren't.

Second test: the signs aren't all the same length

The 1/12 expectation isn't quite exact. Zodiac periods don't all span the same number of days, and leap years add a day to Pisces. A second comparison therefore calculated the expected count based on each birth year and the actual number of days tied to each sign.

Among the 733 people born in 1900 or later, the result is very close: p = 0.057. But both of these comparisons still share an important limitation. They assume that, aside from calendar length, births are uniform throughout the year. In reality, they aren't.

The real challenge: birth seasonality

Humans aren't born at the same rate every month. That seasonality varies by place and by era. To seriously test a zodiacal overrepresentation, the ideal would be to compare each person to the birth distribution of their own population, in their own time.

But the corpus is international and spans 1710 to 2002. Building a perfectly adjusted worldwide reference would require comparable historical series for dozens of territories across several centuries. Simply using recent French birth data as a control would have introduced a massive time and geography bias.

So I settled on a narrower but more defensible comparison: people whose birthplace was unambiguously tied to the United States, born between 1950 and 1979. For those years, official National Center for Health Statistics tables provide the number of US births by month.

The best-controlled test

This analysis covers 139 people. For each one, the expected distribution accounts for the actual seasonality of US births during their birth year. At the monthly level, p = 0.438: a gap at least this large would show up roughly 44 times out of 100 if the dates simply followed ordinary seasonality. So there's nothing unusual about the observed monthly distribution.

To get back to signs, monthly births were spread across the days of each month, then aggregated by zodiac boundaries. That conversion assumes births are uniform within a given month — an explicitly documented approximation. The zodiacal test gives p = 0.523: a ranking at least this irregular would show up roughly once every two times with no zodiacal preference at all. That's the opposite of a rare signal.

The largest positive gap in this sub-sample actually belongs to Leo, with 18 people observed versus 12.44 expected. But that gap is only 1.58 times the usual variation around the expected count. To start talking about a signal, two things would have been needed: first, that the overall distribution across the twelve signs be itself abnormal — which it isn't, at p = 0.523 — and then that one sign hold onto a strong enough gap after accounting for the fact that we're examining twelve of them. So there's no magic number, like "20 Leos," that alone would settle it: the verdict depends on the whole distribution. Here, neither Leo, nor Scorpio, nor any other sign meets those conditions.

What the analyses show, taken together

• 824 humans, twelve uniform signsp = 0.131
• 824 humans, real sign lengthsp = 0.055
• 733 people born in 1900 or laterp = 0.057
• 271 strictly identified Americans, calendarp = 0.431
• 139 Americans, historical monthly seasonalityp = 0.438
• 139 Americans, demographic zodiacal expectationp = 0.523

No overall test crosses the conventional 5% threshold. This doesn't prove every possible distribution is perfectly identical, nor that a tiny association would be undetectable in some other corpus. It means the data and comparisons carried out here provide no statistical evidence that any particular sign is overrepresented.

Why the myth still feels convincing

A ranking is a story-generating machine. It always produces a winner, a last place, and a few gaps that are easy to comment on. If Scorpio lands high, people point to its intensity. If Gemini lands high, people talk about a split personality. If Pisces comes first, there's always a story to invent after the fact about their emotional depths.

This kind of reasoning starts from the result and builds its explanation backward. It never asks whether the gap was expected, whether the reference population is relevant, or whether the same story would have been told with a different ranking.

What this investigation doesn't claim to show

• The Wikidata corpus is not an exhaustive census of every serial killer, and it depends on Wikidata's own classifications.
• The full corpus is international and historically uneven; there's no perfect worldwide demographic reference here.
• The strongest demographic analysis covers only 139 American people born between 1950 and 1979.
• Converting months to signs assumes an even spread of births within each month.
• The absence of a significant result is not absolute proof that no effect, however small, could exist in some other corpus.

Finally, this study isn't trying to "prove astrology wrong." It tests one precise, falsifiable claim: that certain signs are statistically overrepresented among the serial killers in the studied corpus.

So, is there a serial killer zodiac sign?

Not in the data analyzed. Pisces leads the raw ranking, Gemini comes last, and Scorpio sits seventh. But none of the overall comparisons — from the uniform expectation to controlling for real historical US birth seasonality — reveals a statistically abnormal distribution across the twelve signs.

So the conclusion isn't that some other sign would have dethroned Scorpio. It's that the ranking, on its own, never let anyone name a sign "predisposed" to crime. In this corpus, with the comparisons carried out, we found no evidence that any particular zodiac sign is overrepresented among serial killers.

Frequently asked questions

Sources and method

• Wikidata — initial corpus assembly, identity metadata and birth dates, later verified and cleaned.
• CDC / National Center for Health Statistics — Vital Statistics Online Data Portal.
• NCHS, Vital Statistics of the United States — 1939–1964 and 1965–1979 volumes. The monthly tables used cover 1950–1979.
• χ² goodness-of-fit tests applied to the overall distribution of the twelve signs. Western tropical zodiac convention, documented and identical across every analysis.

Observational, exploratory analysis ✦ The results describe this corpus and are neither an individual criminological profile nor a causal claim about astrology. 🌙