Holiday Calendar

National Dennis Day

Next celebratedSaturday, November 21, 2026

Peter Abelard was driven out of France in the 1100s for pointing out that the two men called Denis were not the same man. The name survived the argument, spent 51 unbroken years in America's top 100, and now has November 21.

Countdown to the day
--DAYS
--HRS
--MIN
--SEC
Last updated September 7, 2026 · by the Holiday Calendar TeamHave an update or spot an error?
YEARLY DATENovember 21
OBSERVED INInternationally
CATEGORYNames
ORIGIN

Community Origin

FOUNDING ENTITY
Not documented
FIRST OBSERVED
Not documented
HOW THE HOLIDAY CAME TO BE

A name day that arrived without an author.

A full-text search of the US Federal Register returns no document naming National Dennis Day. No founder, first observance, or sponsoring organisation could be located.

+ Know the story? Submit a founder Help us complete this holiday
INTRO

Two Dennises arrived in print on the same day

National Dennis Day sits on a name with an unusually crowded record. On 12 March 1951, a comic strip about a five-year-old troublemaker called Dennis the Menace ran in 16 American newspapers. The same day, a British weekly called The Beano launched its own Dennis the Menace, a boy of ten.

The two cartoonists had never heard of each other. Both strips went on sale that same day, one in California and one in Dundee, and both ran for decades afterwards.

The tidy conclusion is that the comics made Dennis a household name. American name records say the opposite. The name was already near its peak when the strips landed, and it had been climbing for years before either boy was drawn.

Advertisement
ORIGINS

Dennis Day history

INTRODUCTION

It starts with a beheading. Around the year 258, in Paris, a bishop named Denis was killed in a persecution of Christians. Britannica calls him allegedly the first bishop of Paris and marks the date uncertain.

The earliest account is thin. The sixth-century Historia Francorum of Gregory of Tours records only that Denis was one of seven bishops sent to Gaul.

CHAPTER 01

A saint, then a case of mistaken identity

In the 800s, Hilduin, the abbot of Saint Denis, translated the mystical works of Pseudo-Dionysius and identified that writer with the Parisian martyr. Two Denises became one.

The correction was not welcome. In the 1100s, Peter Abelard sought to show that the two Denises were not the same person. He was driven from the monastery and from France.

CHAPTER 02

The Normans carry Denis to England

The name travelled better than the argument. Denis was common in France through the Middle Ages, and the Normans imported it to England, where it is now regularly spelled Dennis.

The doubled spelling turns up in the parish record. A citation edition of medieval European names records the Dennis spelling in English registers in 1541.

CHAPTER 03

An American century, and a day nobody signed

The American record picks up in the 1930s. Dennis entered the Social Security Administration's top 100 for boys in 1934. It held a place there for 51 unbroken years.

The comic strips arrived in the middle of that run. Hank Ketcham was hunting for a name when his wife Alice burst into his studio to report that their four-year-old, Dennis, had wrecked his bedroom instead of napping.

National Dennis Day is the one part of the story nobody wrote down. The name under it reaches back to the third century. The day sitting on top of it has no traceable beginning at all.

TIMELINE

Timeline

Denis is martyred near Paris

Britannica dates the death of the first bishop of Paris to 258 and marks the year uncertain.

Abelard flees over a name

Peter Abelard was driven from France after arguing that the Parisian Denis and the Athenian Denis were two men.

The Dennis spelling reaches English registers

English parish and marriage registers record the modern spelling that year in a citation edition of medieval names.

Dennis enters the American top 100

Social Security records place the name inside the top 100 for American boys for the first time.

Two Dennis the Menaces debut

Hank Ketcham's strip and The Beano's launched on 12 March, on opposite sides of the Atlantic.

The top 100 run ends

Dennis slipped to 103rd among American boys' names and has not been inside the top 100 in any year through 2025.

WHY THIS DAY MATTERS

Why National Dennis Day Matters

RECORD

A name day that can be checked, not just felt.

Most name days rest on sentiment and little else. This one sits on a public dataset that has counted the name in the United States every year since 1880.

REACH

The name has run from kings to film directors

A Portuguese king of the 1100s and 1200s bore the name, and so did the philosopher Denis Diderot in the 1700s. Dennis Hopper took it onto film, directing and co-writing Easy Rider in 1969.

BY THE NUMBERS

National Dennis Day by the Numbers

#16
Dennis's peak US rank, 1949
24,552
US boys named Dennis, 1952
#707
Dennis's US rank, 2025
381
US boys named Dennis, 2025

MYTH VS FACT

Common Misconceptions

The myth

The Dennis the Menace comics made Dennis a popular name.

The truth

Social Security records put Dennis 17th among American boys' names in 1950 and again in 1951, the year the strips debuted. The name had been inside the top 20 every year since 1942, nine years before either boy reached print.

The myth

Every Dennis traces back to the Greek name.

The truth

Not always. The same reference records Dionysius being used as a latinisation or anglicisation of the Irish name Donnchad, which is also the root behind Duncan.

GOOD TO KNOW

Surprising facts about National Dennis Day

Saint Denis is invoked against headaches

Britannica names him a patron saint of France and of Paris, and adds that he is invoked by people suffering from headache. A legend recorded in the 9th century has his decapitated body carrying his head two miles while preaching.

The Beano's Dennis waited weeks for his stripes

He arrived in March 1951 without the black-and-red striped jumper he is known for, which reached him on 5 May. His dog Gnasher did not turn up until 1968.

A music hall song may have named him

Mike Stirling, head of Beano Studios Scotland, says the British Dennis was named, reputedly, after a music hall song of the time: 'Dennis the Menace... from Venice'.

A Dennis wrote the C programming language

Dennis MacAlistair Ritchie created C and, with Ken Thompson, the Unix operating system. The two shared the Turing Award in 1983.

Records hold 621,000 American Dennises

Social Security data lists 621,000 boys named Dennis from 1880 through 2025. The files cover card applicants and exclude names with fewer than 5 occurrences, so the real total is higher.

GET INVOLVED

How to Observe National Dennis Day

EDITOR'S PICK

Look up the name in the federal name records

The Social Security Administration publishes a count for almost every name in every year back to 1880. Download the national data and see how many boys shared the name the year a Dennis you know was born.

ASK

Ask a namesake where the name came from

Family naming stories are rarely written down anywhere. Ask a Dennis how the name was chosen, and record the answer while there is someone to ask.

MARK

Mark the other Dennis date on the calendar

The French church keeps the name day for Denis on 9 October, tied to the saint himself. Check the French register and give the Dennis in your life two dates instead of one.

TRACE

Trace the spelling through medieval records

A scholarly citation edition lists dated attestations of the name country by country. Search its entry for Dennis and follow the spelling from Latin into English.

Test your knowledge

How well do you know National Dennis Day?

1 / 8

On what date did the two unrelated Dennis the Menace strips first appear?

Answer

No. It is an unofficial observance with no legal standing on record, so 21 November is a normal working day.

COLOPHON

Sources

How we know what’s on this page. References, not endorsements.

12sources
4primary records
1independently dated
Primary records
US Social Security Administration
Popular Baby Names: Beyond the Top 1000 Names
The national name files, and the rule excluding names with fewer than 5 births a year.
View source
Dictionary of Medieval Names from European Sources
Dennis
Dated attestations of the name across Europe, with its Greek and Latin derivation.
View source
Nominis, Conference of Bishops of France
Prenom Denis
The French church's register listing 9 October as the name day for Denis.
View source
US Federal Register
Document search for National Dennis Day
A full-text search of federal documents, returning nothing for the day.
View source
Additional coverage
Encyclopaedia Britannica
St. Denis
The saint's uncertain dates, his patronages, and the medieval mix-up over his identity.
View source
The Courier
The curious tale of two menacing children named Dennis
Beano Studios on the two strips reaching print on the same day in March 1951.
View source
Smithsonian Magazine2016
Dennis the Menace Has an Evil British Twin
How two cartoonists invented the same character in the same week, and how they differed.
View source
Behind the Name
Denis
The medieval French forms and the Norman route that carried the name into England.
View source
Wikipedia
Hank Ketcham
The October 1950 studio scene in which the cartoonist's son gave the strip its name.
View source
Wikipedia
Dennis the Menace (U.S. comics)
The American strip's 1951 launch in 16 newspapers and its Wichita setting.
View source
Wikipedia
Dennis Ritchie
The computer scientist behind C and Unix, and the 1983 Turing Award he shared.
View source
Wikipedia
Dennis Hopper
The actor and director, and his 1969 debut feature Easy Rider.
View source
YOU MIGHT ALSO LIKE

Related holidays

THU
08
Jul 2026
National Denise Day
Names

National Denise Day

A day belonging to a name America took up fast and put down: Denise has missed the top 200 in every decade since the 1980s, yet the spelling was already in England's poll tax lists of 1381.

128Read
MON
22
Mar 2026
National Donald Day
Names

National Donald Day

Donald came out of Scotland meaning ruler of the world, carried by kings and made common by the clan that took it for its own. National Donald Day sits with that name and not the cartoon duck, who has a June day of his own.

80Read
THU
22
Apr 2026
National Terry Day
Names

National Terry Day

Most Terrys were named decades ago, so National Terry Day tends to land on the older people in a family. Call rather than post, which is the difference between marking a day and keeping it.

80Read
FOR MARKETERS & CREATORS

Turn every day into a moment your audience actually shows up for.

8.4M
Monthly readers
5K+
Holidays tracked
Holiday Calendar for Brands Developer API