Adonis, who died in Aphrodite's loving arms, was killed by a boar that might have been sent by a jealous Ares.
The 4th Labor of Hercules was the capture of the Erymanthian Boar.
A boar was sacrificed to Freyr at the Winter Solstice. Amid trumpets blaring and minstrels singing, the boar's head with an apple in its mouth, was carried in on a gold or silver platter.
Here is a familiar version (from a publication by Thomas Wright in 1841) of the Boar's Head Carol that was first published in 1521, with translation of the Latin.
The boar's head in hand bear I
Bedecked with bay and rosemary
I pray you, my masters, be merry
Quot estis in convivio.
(However many are at the feast)
||: Caput apri defero,
Reddens laudes domino. :||
(I bring the boar's head,
giving praises to the Lord)
The boar's head, as I understand,
Is the rarest dish in all this land,
Which thus bedecked with a gay garland
Let us servire cantico
(serve with song).
[A tastier version of this line:
Servitur cum sinapio.
(It is served with mustard)]
Our steward hath provided this
In honor of the King of bliss
Which, on this day to be served is
In Reginensi atrio
(in the Queen's hall).
First stanza repeats.
Source: "The 'Boar's Head Carol' and Folk Tradition" James E. Spears Folklore, Vol. 85, No. 3. (Autumn, 1974), pp. 194-198.