The phrase not just a pretty face designates a person who has qualities other than mere attractiveness, especially intelligence—often without the implication that the person referred to is particularly attractive.
However, in early use, the phrase was (just) a pretty face, and specifically designated a woman who had no qualities other than attractiveness—with connotations of low intelligence, or of flightiness, or (importantly) of low social status and poverty.
The earliest occurrences of the phrase (just) a pretty face that I have found are as follows, in chronological order—many are from novels and short stories by women writers:
1-: From Chapter 8 of Julian Cristie, by ‘Morphine’, written for, and published in, The Tralee Chronicle (Tralee, County Kerry, Ireland) of Friday 16th January 1857:
“What married woman in a hundred is it that does or knows her duty, I’d be glad to know? […] And the husbands may thank themselves,” continued Miss Crone. “Which of them deserves respect? Whom do they select for wives? Who but showy nothings, or silly dawdles, with a pretty face and nothing else in the world to recommend them—creatures they think incapable of discovering their own want of sense and discrimination.”
2-: From Our Family Picture, an unsigned story published in The Londonderry Sentinel (Derry, County Derry, Ireland) of Friday 1st January 1858:
Olive was not the sort of person calculated, as a wife, to make him happy. She was so light and volatile, so changeful and full of whims, so different from Philip in disposition and temper, that for all her beauty and pretty, saucy ways, it was a mystery to me how an attachment could ever have sprung up between them. But, then, Philip was not the first man of sense that has been entangled by a pretty face with nothing behind it.
3-: From Was it a failure?, a short story by D. R. Castleton, pen name of Caroline Rosina Derby (1805-?), published in Harper’s New Monthly Magazine (New York: Harper & Brothers, Publishers) of July 1873—Margaret, who is in love with Edward, her stepbrother, has just learnt that he got engaged to a poor girl called Fanny:
“But, sister, you are unjust, you are prejudiced; you do not know Fanny.”
“Whose fault has that been, Edward? No, I do not know her, but I have heard of her.”
“What have you heard?” said Edward, flushing up hotly.
“Nothing, in the way you mean,” said Margaret, calmly. “I have heard that she is a pretty face, and nothing more; as unfitted to be your wife, Edward, as you are unfit to be her husband.”
4-: From the review of Tinsley’s Magazine (London, England), published in The Portadown & Lurgan News, and County Armagh Advertiser (Portadown, County Armagh, Ireland) of Saturday 26th September 1874:
We have poetry; but there is not very much to be said about it. It is in the usual magazine style, and there is one piece of an especially ephemeral character. It is about a pretty face, which is “no more.” A pretty face is doubtless a very pretty thing, and it offers good ground for unlimited rhapsody about azure eyes, and snowy brow, and ruby lips, but if a pretty face has nothing but its prettiness to recommend it, it is but a poor thing after all; and as we hear of nothing at all in this effusion but lips and eyes, and the like, we really cannot sympathise with the grief of a person who “knew a face.” The loss of a pretty face is, fortunately, not irreparable. There are plenty of pretty faces left, and one is as good as another. There are as good fish in the sea as ever were caught; and when it is only a matter of mere empty prettiness, we are fain to tell this dejected person to pluck up courage, get another pretty face—not by any means a difficult undertaking—and make “love to the lips that are near,” as Moore advises. Had there been anything behind the pretty face, the matter would have been different; but magazine poetry rhapsodises about faces which are merely pretty, and girls who are seventeen or sixteen, or some other age, which is supposed to bring a peculiar charm with it, in a sickly, sentimental fashion, which is not over pleasant.
5-: From A Queer Mistake, a short story by Mrs. M. H. Field, published in The Overland Monthly (San Francisco: John H. Carmany & Company) of May 1875:
Hitty’s husband was a brakeman on our new railway, and had been killed a few months before. He had been a very good husband to Hitty—this strong, good-natured, careless young Eastman—and when he was taken away from her she seemed to have no spirit left in her. In truth, she never had had much; just a pretty face—that was all there was of Hitty Hix. Her mother had lived with her until her husband’s death, and then, as there was nothing for them to live on a single month, old Mrs. Hix was taken to the poor-house, while John Eastman’s brother—a poor man with a large family—offered a temporary home to Hitty.
6-: From Chapter 6 of Christy’s Inheritance. A London Story (London: Henry S. King & Co., 1876), by Florence Whitaker:
“The old Squire was as proud as proud of his fine blood and high family; and, what was more, he’d always set his heart on his son’s marrying young Lady Jane Duncan, at Eastover Park, for you see the estates touch each other, and it would have been a fine thing to have them joined. And then to hear of his taking up with nobody knew who, quite a common sort of girl, by all accounts, with just a pretty face and not a penny to her name. That were too much for Sir John, so he wrote to say as he’d cut him off with a shilling, and never see his face again, if he didn’t drop all that nonsense and come back and settle down, like a sensible man, and marry where his friends wished him. And, as to the poor girl, he’d see as she was made comfortable.”
7-: From Chapter 5 of Under which Lord? (London: Chatto & Windus, 1879), by the British novelist and journalist Eliza Lynn Linton (1822-1898):
“She need not have been crushed. She need not have given in to that vile husband of hers if she had not liked it,” she said. “Really, no excuses are to be made for her, Superior! She is just a child with nice manners and a pretty face and nothing whatever in her. When you have said that she is kind-hearted you have said all for her that you can. Of mind she has not a trace.”
8-: From Chapter 9 of How it all came round (London: Hodder and Stoughton, 1883), by L. T. Meade, pen name of the Irish novelist Elizabeth Thomasina Meade (1844-1914):
“He met his second wife and married her. I don’t pretend,” continued Uncle Jasper, “that we liked this marriage or our step-mother. We were young fellows then, and we thought our father had done us an injustice. This girl he had chosen was an insipid little thing, with just a pretty face, and nothing whatever else. She was not quite a lady. We saw her, and came to the conclusion that she was common—most unsuited to our father.”
9-: From Chapter 4 of The Fifth of November on Plympton Green; Or, The Cruise of the “Nereid”, by Mrs. Frederic Jackson, published in Doidge’s Western Counties’ Illustrated Annual: A Miscellany of Useful, Instructive, & Entertaining Local and General Information (Plymouth (Devon, England): Doidge & Co., Publishers, Booksellers) for 1884:
“Don’t grieve about Dennis’ marriage now dear, it may prove a blessing to us, and what more do we wish for than our boy’s true happiness.”
“That’s just like a woman’s reasoning, Melora, what blessing as you call it, can come out of his choosing a beggar girl like that; no money—no family—what good can she do him; just a pretty face! and that’s all that boys think of.”
10-: From Beatrice (London: Longmans, Green, and Co., 1890), by the British novelist Henry Rider Haggard (1856-1925):
[Chapter 16] In this matter of his experience of the previous night, and generally of the strange and almost unnatural sympathy in which he found himself with this lady, common sense and the results of his observation and experience pointed to the whole thing being nonsense—the result of “propinquity, Sir, propinquity,” and a pretty face—and nothing more.
[Chapter 20] “Just fancy a man like that pining for a village girl—she is nothing more! And they talk about his being so clever. Well, he always liked ladies’ society; that is his failing, and now he has burnt his fingers. They all do sooner or later, especially these clever men. The women flatter them, that’s it. Of course the girl is trying to get hold of him, and she might do worse, but so surely as my name is Honoria Bingham I will put a spoke in her wheel before she has done. Bah! and they laugh at the power of women when a man like Geoffrey, with all the world to lose, grows love-sick for a pretty face; it is a very pretty face by the way.”
11-: From Chapter 2 of The Laird o’ Cockpen, by ‘Rita’, pen name of the British novelist Eliza Humphreys (née Gollan – 1850-1938), published in All the Year Round: A Weekly Journal. Conducted by Charles Dickens (London: Charles Dickens and Evans, Crystal Palace Press) of Saturday 4th October 1890:
“The ‘Laird o’ Cockpen,’ as we call him, […] he’s a great politician, and very good, and very charitable, and a great pillar of the Free Kirk. More than all, he wants a ‘braw wifie,’ and many’s the lass that’s set her cap at him; but he’s not just easy to please—and he’s not so young as to be snared easily by just a pretty face, and no more. Now, wee coz, suppose he took a fancy to you—my, but that would be a fine thing! He’s rich, he has a beautiful place called Corriemoor, and he’d make an excellent husband I’m sure.”
12-: From Chapter 5 of Little Miss Uraca. A Modern Love Story, by the British novelist Evelyn Everett-Green (1856-1932), published in The Young Woman: A Monthly Journal and Review (London, England) of Friday 3rd February 1893—the adjective portionless means without a dowry or dower:
“Edna must be two or three-and-twenty, and she has been out for four or five seasons, and is always to be seen at any local gaiety, summer or winter. I fancy she must be something of a doll—just a pretty face and nothing behind. In these days men are just a little afraid of portionless girls with expensive tastes and no brains. In a London season she might have a chance, but down here it seems as though none of them would ever go off.”
The following, from the Warwickshire Herald and Midland Counties Advertiser (Birmingham, Warwickshire, England) of Thursday 17th October 1889, mentions a religious perspective on the phrase (just) a pretty face:
THE REV. J. SHILLITO, OF SUTTON COLDFIELD, ON FEMALE BEAUTY.
On Sunday evening last, the Rev. J. Shillito delivered his second lecture on the Book of Esther, the subject being “The Fortunes of a Jewish Maiden.” Referring to the orphan Esther being chosen to succeed Vashti as Queen of Persia, on account of her beauty, the preacher said: Beauty is of various kinds, there is beauty of the body, the symmetry of form and feature, the loveliness of complexion and colour, the charm of grace and elegance of movement and demeanour. There is beauty of the mind, grandly independent of externals, which often looks out and exercises a mightly influence from a plain and even deformed body; and there is beauty of the spirit, soul in its perfect flowering, full of love and mindliness. Esther seemed to have had the glowing physical beauty which belongs to many of her Jewish race, and to this was added, if he read her story aright, the charm of a well-balanced mind, and of a gentle, loving soul. Is not this the perfection of beauty when a fine mind and a loving soul give expression to a beautiful face and figure? And should we not learn from Esther that the higher qualities of the mind and soul are more to be prized and cultivated than mere outward attractions? Beauty she had of a dazzling captivating kind; but, if this were all, she would not have been the woman she was. Let us not disparage, or despise, personal beauty. It is a heaven born gift. It is lovely to look upon. It charms all beholders. But, if we have this, and nothing else, we have not the highest style of beauty, nor the most permanent attractions. The beauty of expression is superior to that of feature. A beautiful face may become positively hideous when distorted by evil tempers—such as anger, jealousy, and envy. A plain face may become positively beautiful when lit up with love and peace and gladness. A pretty face, and nothing more, is an empty charm. A fine mind, cultivated and evenly balanced, is a great treasure. A large loving soul, full of kindness and benevolence, is a pearl of the greatest price. Religion, more than anything else, will give to beauty of the person a fresh loveliness—a sweetness all its own. Religion hallows and hasten the mind, and gives to it a refinement and simplicity which nothing else can give. Religion will enlarge and expand the soul, and fill it with lofty impulses and aspirations, which rise above earth and time. “Favour is deceitful and beauty is vain, but a woman that feareth the Lord she shall be praised.”