The story of King David is recounted in 1 Samuel 16-31 and 2 Samuel 1-24.
Many of the Psalms are headed "Psalm of David" and he was taken to be the composer of the entire Psalter. Because of this presumption, King David's attributes are a harp and whatever signifies royalty at the time of the painting. For most of the high middle ages that means a crown, usually pictured as a low and spiky diadem as in the first image at right. The choice of a mere diadem rather than a more elaborate crown is probably due to the Latin of 2 Samuel 1:10, where an Amalekite takes the diadema from the dead Saul and passes it on David as Saul's successor.
Before the medieval period David's kingship is expressed not by a crown but by such signifiers as his standing under an imperial arch (example) or sitting on a throne (as in the second picture at right, which bears a strong resemblance to this 2nd/3rd century image on a probably non-Christian sarcophagus).
As for the harp, it is often pictured as the kind of lyre seen in the second picture at right. Sometimes it can be a "psaltery," a box with strings over a sound hole as in the first picture at right or this Renaissance example.
Instead of a harp, this Romanesque ivory asserts his authorship by placing him on a throne dictating to four scribes, and this 18th-century portrait places a quotation from the Psalms on his shield.
King David is often seen in Orthodox images of the Anastasis (example) and, less often, in western "Harrowing of Hell" images (example. In Annunciations he also sometimes figures among the prophets believed to have foretold that event (example).
Prepared in 2014 by Richard Stracke, Emeritus Professor of English, Augusta University, revised 2015-10-21, 2017-04-10, 2018-07-30.