The Earl O March's Daughter
Jean Douglas was the youngest daughter of William Douglas, Earl of March (1724-1810). Forbidden to marry the son of the laird of Tushielaw, who was considered below her station, she pined while her lover was exiled. When Tushielaw returned, Jean was so ill that he didn't recognise her, and she died broken hearted. Jean haunts Neidpath Castle and appears clad in a full-length brown dress with a large white collar. Sir Walter Scott also wrote a poem about her, although in my opinion, it's nowhere near as good as Lionel's song.

The Maid of Neidpath
by Sir Walter Scott

O lovers' eyes are sharp to see,
And lovers' ears in hearing;
And love, in life's extremity,
Can lend an hour of cheering.
Disease had been in Mary's bower,
And slow decay from mourning,
Though now she sits on Neidpath's tower,
To watch her love's returning.

All sunk and dim her eyes so bright,
Her form decay'd by pining,
Till through her wasted hand, at night,
You saw the taper shining;
By fits, a sultry hectic hue
Across her cheek was flying;

By fits, so ashy pale she grew,
Her maidens thought her dying.
Yet keenest powers to see and hear
Seem'd in her frame residing;
Before the watch-dog pricked his ear
She heard her lover's riding;
Ere scarce a distant form was ken'd,
She knew, and waved to greet him;
And o'er the battlement did bend,
As on the wing to meet him.

He came—he pass'd—an heedless gaze,
As o'er some stranger glancing;
Her welcome, spoke in faltering phrase,
Lost in his courser's prancing.
The castle arch, whose hollow tone
Returns each whisper spoken,
Could scarcely catch the feeble moan
Which told her heart was broken