Hornswoggle was the primary antagonist in the early 80's animated series, The Gary Coleman Show. In this show, Coleman played an apprentice angel, Andy LeBeau, tasked with helping others in order to get into Heaven. Hornswoggle was his enemy, trying to trick him or thwart his efforts (Hornswoggler is a term used to describe a deceptive sort, usually a huckster or scam artist). For some reason never explained in the series, Hornswoggle seemingly cannot be seen or sensed by Andy's supervisor "Angie", who firmly believes he is only making Hornswoggle up. Angie is in fact so infuriatingly bureacratic, she almost qualifies as a secondary antagonist. Hornswoggle can be very deceptive and clever, but never truly vicious, except that he was possibly dooming a young soul, though the possible consequences of Andy's failure are never brought up. The situation was based on Coleman's 1982 TV-Movie, The Kid With The Broken Halo.
In the series
Nothing is ever explained about his exact identity, who may be behind him, or if he is truly a demon of some kind. He does delight in his work, and the naive LeBeau made his work all the easier. That said, his schemes were usually able to be seen through with some thought or observation, and once known of, LeBeau was usually able to turn the tables on him pretty effectively. Perhaps his most devious scheme was using a life-size puppet of Angie (who again, never questioned the persistence of Andy's claims) to mis-guide Andy into a lot of trouble. But once Andy caught on, he was able to reverse the deception, making Hornswoggle think he had been bamboozled once again and even using the puppet to scare the creep off, making him think he had been exposed at last. Like many another magic-using kid on TV, Andy LeBeau often brought a lot of grief on himself through foolish use of his powers, but without Hornswoggle, the situations would never have escalated as far as they did. The series was not long-lived, and many of these conflicts and questions went unresolved.