John King
According to Readers Guide to The Mahatma Letters to A. P. Sinnett:
King, John, a well-known materialization in spiritualistic circles in the 1870's. Somewhat mysterious in character and generally claiming to be the spirit of the pirate, Henry Morgan. There are several references in occult literature to the employment by Adepts and other proficients in the occult arts of elementals and elementaries for accomplishing work which they wish to have done. HPB aparently used John King in this manner for some time while in the USA. A picture of him produced jointly by him and HPB is at the Headquarters. ML, p. 277; HPB VI: 270-71; HPB Speaks I: 83 et seq.[1]
Mme. Blavatsky writes:
I have known and conversed with many a "John King" in my life—a generic name for more than one spook—but, thank heaven, I was never yet "controlled" by one![2]