"Great Scott!” is an exclamation of surprise or amazement that was popular in the 19th century. The origin is unclear, but “Scott” is used in a similar way to the German “mein Gott” ("my god").
The Scottish historical novelist Walter Scott (1771-1832) was frequently called “the great Scott,” but it’s not known if this had any influence on the “great Scott” expression. “Great Scott!” has been cited in print since at least 1845. The expression was popular with military men who served under U.S. Army General Winfield Scott (1786-1866), as explained in 1852:
“The exclamation of ‘great Scott,’ so frequently used by many people, is said to allude to Gen. Scott, the whig candidate for President.”
Wiktionary: great Scott
May come from Gen. Winfield Scott of the American Civil War, who weighed about 300 pounds and was referred to by his troops as “Great Scott”.
1. (dated) An exclamation of surprise or amazement
Wikipedia: Great Scott
Great Scott! is an interjection of surprise, amazement, or dismay. As a distinctive but inoffensive exclamation, popular in the second half of the 19th century and the early 20th century, and now considered dated. It presumably originates as a minced oath, but has also been associated with specific “Scotts”, notably US general Winfield Scott and Scottish author Sir Walter Scott.
It is frequently assumed that Great Scott! is a minced oath of some sort, Scott replacing God. The 2010 edition of the Oxford Dictionary of English labels the expression as “dated” and simply identifies it as an “arbitrary euphemism for Great God!“. Alternatively, it has been suggested that it may be a corruption of the German greeting Grüss Gott.
Wikipedia: Winfield Scott
Winfield Scott (June 13, 1786 – May 29, 1866) was a United States Army general, and unsuccessful presidential candidate of the Whig Party in 1852.
Known as “Old Fuss and Feathers” and the “Grand Old Man of the Army,” he served on active duty as a general longer than any other man in American history, and many historians rate him the best American commander of his time. Over the course of his 53-year career, he commanded forces in the War of 1812, the Black Hawk War, the Mexican–American War, the Second Seminole War, and, briefly, the American Civil War, conceiving the Union strategy known as the Anaconda Plan that would be used to defeat the Confederacy. He served as Commanding General of the United States Army for twenty years, longer than any other holder of the office.
7 March 1845, The Spirit of Democracy (Woodsfield, OH), “The Bank Bill,” pg. 2, col. 5:
The great fine-and shearing (financiering) scheme of Mr. Kelly, has become the law of the land; and this bill of seventy five sections we promised to publish, should it finally passed into law. Great Scott! is it possible that we ever promised to publish this law.
28 July 1852, Madison (IN) Daily Banner, pg. 2, col. 3:
The exclamation of “great Scott,” so frequently used by many people, is said to allude to Gen. Scott, the whig candidate for President.
Penn State University Libraries
1 October 1857, Philadelphia (PA) Press, “Speech of Benjamin Rusk, Esq.,” pg. 4, col. 1:
He referred to the famous Dred Scott decision. he once knew an office of the army, who, whenever he became very emphatic, had a habit of invoking his great commander, and was apt to exclaim, “Great Scott!”
California Digital Newspaper Collection
10 May 1861, Sacramento (CA) Daily Union, “Letter from New York,” pg. 1, col. 5:
Jolly! Great Scott!
Miss Ravenel’s Conversion from Secession to Loyalty
By John William De Forest
New York, NY: Harper & Brothers
I follow General Scott. No Virginian need be ashamed to follow old Fuss and Feathers. We used to swear by him in the army. Great Scott! the fellows said.
Eye of the Storm:
A Civil War Odyssey
By Robert Knox Sneden
Edited by Charles F. Bryan, Jr. and Nelson D. Lankford
New York, NY: Touchstone
(Diary entry of May 3-8, 1864.—ed.)
“Great Scott,” who would have thought that this would be the destiny of the Union Volunteer in 1861–2 while marching down Broadway to the tune of “John Brown’s Body,” etc?
15 May 1892, Cleveland (OH) Plain Dealer, “A Soldier Hermit. The Secluded Life Now Led By Gen. Alfred Pleasanton. The Latter Days,” pg. 9, col. 5:
Gen. Pleasanton is a man who never profanes his lips with an oath, nevertheless he is not guiltless of the use of epithets. Years ago, before the now familiar exclamation “Great Scott!” dotted the columns of the newspapers of the country, he used it as his most frequent substitute for the expression of a meaning generally conveyed by the use of downright vulgarity and profanity. He was doubtless the inventor of that odd phrase, suggested by the wonderful campaigns of Gen. Scott in Mexico, and it is a pity, perhaps, that he did not file a caveat to cover it, or have it copyrighted for his own especial use and benefit. At any rate it has served the purpose thousands of times, in print and otherwise, of giving vent to both humorous and serious emotions. But his greatest and most forcible epithet is “Great Caesar’s ghost.” When he hurls these words through his teeth, albeit his voice is soft and pleasant to the ears of his listeners, he conveys an impression of earnestness, indignation or surprise that does not reside in any other vehement and italicized expression.
Dictionary of Phrase and Fable
By Ebenezer Cobham Brewer
Philadelphia, PA: Henry Altemus Company
Great Scott or Scot! A mitigated form of oath. The initial letter of the German Gott is changed to Sc.
OCT. 21 2015 8:02 AM
Great Scott! Who Was Scott? The Origin of Doc Brown’s Favorite Phrase, Explained.
By Forrest Wickman
Today is Back to the Future Day, the day when we finally reach the precise date of Back to the Future II, survey the fact that we got memes instead of hoverboards, and utter Doc Brown’s favorite exclamation: “Great Scott!” But who was Scott?