John Wilkins points to an article describing a Catholic school in Australia tried to refuse to enroll a child because his last name was Hell. It's very unfortunate. It's also a sign at how ignorant Catholics often are of their heritage, because no one could do such a thing who had ever heard of Father Maximilian Hell, S.J.
Father Hell was one of the greatest astronomers of the eighteenth century; as astronomical knowledge has advanced it has repeatedly shown Hell to have been extraordinarily careful and accurate in his investigation of the sky. One of his major scientific endeavors was a scientific expedition into the Arctic Circle in order to track the transit of Venus across the sun in 1769, in one of the earliest examples of major international scientific cooperation. While there Father Hell and his team began collecting mineralogical and biological data for an encyclopedia devoted to the arctic regions.
However, after this point, Hell began to undergo a series of trials. The first was a dispute with the French Academy over the reporting of his results. Because of Hell's reputation for accuracy, people from all over Europe tried to get his results, but since Hell had been sponsored by the Danish king, he felt he had an obligation to report his results to his Danish sponsor before doing so to anyone else. This led to a publication delay, and the French Academy, somewhat angered by the perceived slight, accused Hell of altering his data in order to make his results closer to results achieved by others. When he published his work, this insinuation died down, but it arose again posthumously when Hell's successor at the Vienna Observatory, Littrow, raised it again on the basis of Hell's manuscripts. Scholarship since then has shown that Littrow was certainly wrong, but for a very long time Hell labored under the suspicion of plagiarism and manipulation of data. He has long since been vindicated, and it has been shown that Hell's original reputation for accuracy was quite right: his results were far and away more accurate than anyone else's at the time.
Unfortunately for Hell, the Society of Jesus was suppressed in 1773, which massively disrupted his scientific work. It is for this reason, for instance, that his encyclopedia on the arctic never materialized.
Hell had an interest in magnetism, and one of his projects in 1769 was an investigation of geomagnetism. This is a good summary (PDF) of Hell's work on this subject. It makes for very good reading. Here are photographs of Hell's manuscripts (PDF, large file).
He has a crater on the moon named after him. The name, Hell, of course, which has become the subject of endless jokes (and endless delightful claims like, "Unfortunately for Hell, the Society of Jesus was suppressed in 1773"), just means 'bright', and could also be spelled Høll.
If you want to know where Hell Crater is, you can look here. The large flat plain is Mare Nubium; to its southeast is a large basin called the Deslandres basin. In the western part of the Deslandres basin is a fairly large, fairly circular crater with well-pronounced sides -- that's Crater Hell. (You can roll the cursor over it to check that you have it right.)