From Wikipedia of the Dark Brotherhood, an online Star Wars Club

Crona, known as "the Other," was the fourth Grand Master of the Dark Jedi Brotherhood, succeeding Kreeayt Havok and preceding Jac Cotelin's first reign.

The Facts

Little is known about Crona, due to missing Dark Voices from the time of his reign. Anecdotal evidence provides only a broad view of the circumstances surrounding Crona:

Kreeayt's Deputy Grand Master, Crona, was the next Grand Master. The exact date of his appointment is unknown, as the first Dark Voice released in his reign is not dated. However, by this time the Brotherhood's membership was reaching 400 and the Obelisk were now an Order within the Brotherhood. More information from former Grand Master Jac Cotelin reveals that during Crona's reign the Brotherhood had slipped into a relative state of torpidity, and that Tau Squadron became a serious source of dissent. After an altercation with the Fleet Commander, the High Court and the Fleet Commander ousted Crona from Grand Master, and expelled him from the Strike Fleet. - Excerpt from "A History of the Brotherhood," retrieved October 13th, 2006, [1]

In Fiction

Fictionally, he is referred as the Other, a dubious title signifying his treachery to the Brotherhood. Driven insane by his own selfishness and connection to the Dark Side, he escaped with a band of followers aboard the Dungeon Ship Lichtor V and was never seen again.

Positions Held
Before Position After
Kreeayt Havok Grand Master
13 ABY - 14 ABY
Jac Cotelin