Selènè mooned the Xerox machine*

Selene, the moon goddess

Every element has its schtick, meaning that each one seems uniquely good at something. Selenium is particularly good at mediating light and electricity via photoconductivity, a property discovered early in its history: shine light on selenium and it conducts electricity better.

Chester Carlson put selenium's photoconductivity to practical use by inventing xerography and founding the Xerox corporation. Carlson patented xerography (which means dry writing in Greek) in 1942 and commercialized it. Selenium's role in xerography was to hold an electrostatic image long enough to attract toner ink for transfer to paper--and then to quickly forget what it saw. Selenium is no longer used in commercial copy machines, but the first ones did. A good historical read is here. Television, then a nascent technology, also used selenium early on. link

Though right next door to arsenic, selenium is not nearly as toxic--though its smell can be nauseating. Selenium disulfide puts the stink in dandruff shampoos, though I'm not sure if it's the selenium or the sulfur--both are chalcogens. Toxic in large doses, selenium is also an essential micro-nutrient, replacing sulfur in amino acids like cysteine and methionine and serving as an anti-oxidant.
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*Element 34, Selenium was named for Σεληνη [Selènè], Greek for Moon. Van der Krogt gives more history of the element's naming. Link