FACT: Despite working very hard to change his image and avoid type-casting, Avery Brooks was constantly "encouraged" to shave his head and grow his goatee beard until he finally relented for the fourth season of DS9.
FACT: Dan Aykroyd was to appear in the TNG episode "Family" as a pointy-headed alien living next door to the Picard family home. The scenes were allegedly never filmed due to "scheduling conflicts", although some sources claim that Patrick Stewart objected to the make-up design of the alien and there was insufficient time to design a suitable alternative.
FACT: John Tesh auditioned for the role of Lt. Worf. As a die-hard Trekkie, he was very enthusiastic and had many suggestions for the character, including the idea that Worf should regularly sing traditional Klingon songs. Ultimately, Michael Dorn was cast instead, but the producers were so taken by Tesh's suggestions for the character that he was called in to write all the songs that Worf sings throughout the series. Tesh later appeared as a Klingon in the episode "The Icarus Factor". Dorn and Tesh sang a duet together in a touching scene with Diana Muldaur, but this was later cut.