Definition of "Mortimer"

He said he would not ransom Mortimer; / Forbade my tongue to speak of Mortimer; / But I will find him when he lies asleep, / And in his ear I'll holla ‘Mortimer!’

c. 1597 (date written), William Shakespeare, “The First Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene iii]

I like the names Herbert and Mortimer more all the time. They are so distinguished and new and American. Do you know how I came to think of them? I was reading the newspaper in bed after my first boy was born. I was reading the society page, which is always so interesting.

1941, Delmore Schwartz, Shenandoah, New Directions, page 13