When an actor can't return for a sequel, sometimes the filmmakers get creative...
This article comes from Den of Geek UK.
Sometimes, things don't go to plan. A movie has hit big, or a franchise is rumbling on, and you want one of the original stars back for the next in the series. The problem? You either knocked them off in the last film, or the actor concerned isn't available, or they just didn't want to return. That, or you didn't want them, but you're too polite to say.
The solution? The photo! Have characters looking mournfully at an image of said actor, just to remind you that they were once part of that particular parish, and so everyone else can acknowledge them, and then get on with it. At least, that's usually how it works.
Here are a few choice examples. As always, help yourself in the comments.