Object Not Showing in Blender Render
Visible in the viewport but missing from the render
Also known as: Blender object missing in render · Blender object not rendering · Disable in renders · Blender camera icon outliner · Blender object invisible render
Quick answer
If an object is visible in the 3D viewport but missing from the render, its render visibility is probably off. Enable the camera icon (Disable in Renders) column in the Outliner filter and make sure it is on for the object, and check that its collection is not excluded. The monitor icon only controls the viewport, so an object can be shown there and still be hidden in the final image.
How to fix it
If the object is still missing, check that it is inside the camera's clip range, that Holdout is not enabled in Object Properties > Visibility, that a modifier's Show in Render icon is on, and that the active view layer includes the collection. In Eevee and Cycles, also look at Render Region and Film > Transparent when the background looks empty rather than the object.