St. Francis invented the nativity scene and snowmen

[Geremia]

St. Francis invented the snowman (St. Bonaventure's bio. ch. 5):

For, by the breath of that infernal enemy, which is wont to kindle the fire of concupiscence, he was assailed by a violent temptation. Then this holy lover of chastity, laying aside his habit, began to discipline himself severely with his cord, saying: "Brother Ass, thus dost thou deserve to be treated, thus to be beaten. Thou art unworthy to wear the religious habit, the sign of purity. Go thy way, then, whither thou wilt, for thus shalt thou go." And then in marvellous fervor of spirit he left his cell, and went out into the garden and plunged into a heap of snow which had just then fallen. Having done this, he gathered the snow in his hands and made seven heaps, which setting before him, he thus discoursed with his interior man: "Behold," said he, "this largest heap is thy wife; these four are thy two sons and thy two daughters; the other two are thy servant and thine handmaid; and for all these thou art bound to provide. Make haste, then, and provide clothing for them, lest they perish with cold. But if the solicitude for so many trouble thee, then be thou solicitous to serve one Lord alone." Then the tempter, being vanquished, departed, and the holy man returned victorious to his cell; and by the intensity of that external cold, to which he had subjected himself, the in terror fire of temptation was so perfectly extinguished, that from that moment he never felt it in the slightest degree. Now a certain friar who was watching in prayer, beheld all these things by the clear light of the moon. And when the man of God knew what he had seen, he made known to him the temptation which he had endured, forbidding him, so long as he should live, to make known what he had seen to any living man.

and nativity scene (ibid. ch. 10):

It happened in the third year before his death, that in order to excite the inhabitants of Grecio to commemorate the nativity of the Infant Jesus with great devotion, he determined to keep it with all possible solemnity; and lest he should be accused of lightness or novelty, he asked and obtained the permission of the sovereign Pontiff. Then he prepared a manger, and brought hay, and an ox and an ass to the place appointed. The brethren were summoned, the people ran together, the forest resounded with their voices, and that venerable night was made glorious by many and brilliant lights and sonorous psalms of praise. The man of God stood before the manger, full of devotion and piety, bathed in tears and radiant with joy; many Masses were said before it, and the Holy Gospel was chanted by Francis, the Levite of Christ. Then he preached to the people around of the nativity of the poor King; and being unable to utter his Name for the tenderness of his love, he called Him the Babe of Bethlehem. A certain valiant and veracious soldier, Master John of Grecio, who, for the love of Christ, had left the warfare of this world, and become a dear friend of the holy man, affirmed that he beheld an Infant marvelously beautiful sleeping in that manger, Whom the blessed Father Francis embraced with both his arms, as if he would awake Him from sleep. This vision of the devout soldier is credible, not only by reason of the sanctity of him that saw it, but by reason of the miracles which after wards confirmed its truth. For the example of Francis, if it be considered by the world, is doubtless sufficient to excite all hearts which are negligent in the faith of Christ; and the hay of that manger, being preserved by the people, miraculously cured all diseases of cattle, and many other pestilences; God thus in all things glorifying His servant, and witnessing to the great efficacy of his holy prayers by manifest prodigies and miracles.