Seventh Day Adventists
This is a Protestant denomination with some heterodox beliefs when compared to more denominations.
It has been around only since the 1800s, and was co-founded by Ellen White, who wrote extensively about her visions and prophecies she claimed to have received from God. This emphasis on a founding, mortal author and the word “Day” in their name, often provokes comparisons to the Mormons (The Church of Latter Day Saints, and their founder, Joseph Smith).
Seventh-Day Adventists believe that the seventh day – Saturday – is the Sabbath, and permit no working on that day. They generally hold church services on Saturday.
Seventh-Day Adventists are much more likely to be vegetarians than other denominations, as White wrote about vegetarianism extensively. White settled in what is now Loma Linda, California. Today, almost half of that city still belongs to the denomination, and it has been noted as an area of exceptional longevity (a “blue zone”).
There are several other aspects of their belief system that don’t quite line up with other Protestant denominations. Whether or not someone’s salvation hinges on these issues is up for interpretation.
Why I Looked It Up
I had often gotten them confused with the Mormons (as noted above).
Also, my church (a mainstream Baptist church) hosted a visiting pastor, and I found out afterwards that a few people had objected because he was a Seventh-Day Adventist.
Honestly, given that very muted response (and given that he returned to preach again a few years later), it would seem that the beliefs of Seventh-Day Adventists and Baptists are not that far apart.