Homn was the attendant of Betazoid Ambassador Lwaxana Troi. He was a tall, pale humanoid man who rarely spoke save in sign language, a skill at which he was quite adept. (TNG: "Haven") Homn possessed strength superior to that of a Human, and frequently consumed very large amounts of alcohol without experiencing any apparent effects. (TNG: "Manhunt")
He often joined Lwaxana Troi on her voyages and was reported to frequently have "outrageously lustful thoughts". (TNG: "Manhunt") Given her penchant for claiming this of many people (Jean-Luc Picard included) the veracity of this assertion is questionable at best.
He had an indulgent temperament in more than one sense of the word. It could be seen in the way he patiently catered to the sometimes exasperating whims of his employer, as well as his quiet indulgences in the "perks" of his employment. For example, he apparently had no inhibitions in finishing off half empty glasses of wine while cleaning up dishes, and once even snacked on the very berries he was sent to pick for his employer. (TNG: "Ménage à Troi")
Neither his species nor his homeworld have been revealed; however, his position and demeanor are very similar to that of a Hupyrian. In the non-canon story "The Ceremony of Innocence in Drowned" in the anthology Tales of the Dominion War, Mr. Homn is killed by the Dominion in their first strike when the Troi household collapses.