I usually try to get these threads up every summer, as that's when trailers for next year's movies often start dropping (as they did last week). As always, this isn't everything on the calendar, as a good chunk of the slate hasn't even been scheduled yet, but it's a pretty solid snapshot as to what 2019 will be offering in terms of major releases.
As a disclaimer, not all dates are wide releases, and please be aware that, starting in 2019, the current week's trailers/titles will be deleted at the end of each week so as to not clog up/overload the post. So, unfortunately, no backlog of trailers and dates.
Anyway, have at it, and please feel free to post trailers as well, just as we've always done, since I will undoubtedly miss a few here and there. In return, I'll keep the OP and the thread as a whole updated as much as I possibly can throughout the year...