Among the kinds of CMEs that can severely threaten much of the life on Earth are the coronal proton ejections (CPE) or Solar Proton Events (SPEs) that have occurred several times in geologic history. One such event today could wipe out much of humanity and leave the Earth devastated. It could bring radiation, massive wildfires, and other destructive events.
The main suspected SPE impacted the earth about 12,900 years ago. There may have two such events, 12,837 years BP and 12,639 years BP. They could have been a principal cause of the final termination of the Pleistocene megafauna and even of several genera of smaller mammals and birds. There is also evidence of one such event in 2012 that missed the Earth by only two weeks. One of the things that it does that could cause mass extinctions is to raise the level of proton (cosmic ray) bombardment to fatal levels. They are also suspected of causing massive, planet spanning wildfires.
There are interstellar objects that might make a grazing contact with the sun, We recently had one such object, Oumuamua, an odd-shaped body about ten times longer than it was wide, with other strange attributes. The general name for interstellar planets, not bound to a particular star, is planemo. Most of them are expected to be round. They could be as large as planets. The term generally applies to a rocky object, likely with a hot core, that could wander among the stars, and could provide a site for an outpost for star travelers, if the core is hot enough to geothermally support such an outpost.