John Mark
Mark 15:17ESV·traditional attribution

And they clothed him in a purple cloak, and twisting together a crown of thorns, they put it on him.

Matthew Henry Presbyterian @wholebiblehenry

Here, I. Pilate, to gratify the Jews' malice, delivers Christ to be crucified, Mar 15:15. Willing to content the people, to do enough for them (so the word is), and make them easy, that he might keep them quiet, he released Barabbas unto them, who was the scandal and plague of their nation, and delivered Jesus to be crucified, who was the glory and blessing of their nation.

Commenting on Mark 15:15-21

John Gill Reformed Baptist @doctorgill

And began to salute him, hail, king of the Jews! In a mock way, wishing him long life and prosperity, as if he was a king just come to his throne, and this was his coronation day. And began to salute him, hail, king of the Jews!

Albert Barnes Presbyterian @notesbybarnes

Verse 17. With purple. Matthew says scarlet. . About his head. In the form of a garland, or diadem. The whole head was not covered, but it was placed in a circle round the temples.