Thomas Dolby wrote synthpop in the earliest part of his career. (The Golden Age of Wireless, The Flat Earth), although he did play keyboards on Def Leppard’s Pyromania album in '83 (credited under the pseudonym “Booker T. Boffin”). He then mellowed out with more stylish pop songs around 1986 (Aliens Ate My Buick). After that he experimented with jazz and soft rock, which he still writes.
Howard Jones is a similar story, writing synthpop/new wave, then straight pop, but after '86 or so, he experimented a lot with ethnic sounds for years. Only on his most recent album a couple of years ago did he switch back pop.
Depeche Mode were a synthpop act throughout the 80s, but in the 90s started introducing a lot more guitar and a more rock sound to their act; with the album Ultra and the first single I Feel You they let rip with electric guitars and a bit of an epic sound. Except for one or two songs, each album since has been either soft rock, or something with a lot of guitar work.
Herbie Hancock was always associated with jazz in some fashion, but in the earlier 80s he entered new wave and contemporary dance music with the seminal classic Rockit. While Rockit was a commercial success, the album Future Shock didn’t do well, nor did the two followup albums in a similar vein – in fact, they are considered the worst of his career, so he returned to his jazz roots, though more modern in style in the form of acid jazz.
Ministry was already mentioned, but Al Jorgensen made the switch because his first releases were under his record company’s direction and he hated them. Once he was able to take his own direction he went with what he was more comfortable with: Metal.