Stark, raving mad
Completely mad; delirious.
When we think of the word stark images of severity or bleak isolation may come to mind. That isn't the meaning of stark in this phrase though, nor incidentally in the phrase 'stark naked'. The 'stark' here has another meaning that is, 'to the fullest extent; entirely; quite'. This was used as an intensifier to 'mad' in the original version of the phrase - 'stark mad'. That version was in use by 1489 when John Skelton used it in The Death of the Earl of Northumberland:
"I say, ye comoners, why wer ye so stark mad?"
'Stark' and 'raving' are just intensifying adjectives so it is correct to add the comma after 'stark', although the phrase is often seen without it; for example, neither the 1999 Stark Raving Mad TV show or the 2002 film of the same name use the comma. Anyone who watches television or reads a newspaper must know how hard intensifiers are expected to work these days and that nothing can be merely 'new'; it has to be at the very least 'brand new' and more often 'brand spanking new'. Things don't change. In the 17th century it wasn't sufficient to be 'mad', nor yet 'stark mad', but 'stark, raving mad'.
'Stark staring mad' was an earlier variant and this was first recorded in John Dryden's Persius Flaccus, 1693:
"Art thou of Bethlem's Noble College free? Stark, staring mad."
By 'Bethlem's Noble College' Dryden was referring to the world's oldest psychiatric hospital The Bethlem Royal Hospital, London. This has been known under several names since its foundation in the 13th century, most famously the colloquial name Bedlam. In Dryden's day only two forms of madness were recognised - Melancholia, what we now call depression, and Raving Madness. 'Stark, staring mad' is still used but is little known outside of the UK.
Henry Fielding used 'stark raving mad' in The Intriguing Chambermaid, 1734 and that was probably the first usage of that version of the term:
"I find I am distracted! I am stark raving mad!"