Unknown people on my Facebook friends list?

[winterbunny]

I was looking through my friends list and there were several people, more than 10, who I know for certain I've heard of or added - and all of them had deactivated pages. I removed them but is there any way to stop this from happening? Has this happened to anyone else? I've never had any problems with anyone hijacking or planting a virus on my page.
What I'm saying is, I never added these people in the first place. I *know* people can deactivate their own page - but that isn't the question. The question is, how does someone get on my friends list when they never sent me a request and I never added them??? That's why I said they are *unknown* -
I don't know them and I never added them.
ETA: I meant to say *never* heard of - hence the reason I called them "unknown people" in the question.

[Safat Islam]

From the information u gave i think there is nothing to be afraid of because as u said those people are known to you. Since they have deactivated their facebook accounts the links to their profile are shown black in color. And no one can plant virus on ur fb page it does not happen like that. What hackers can do is steal ur identity e.g. ur password. So, pls dont be afraid i hope there is no virus.
And u asked about stopping this from happening that is not possible any of your friends can deactivate their account and their profile link will turn black on ur friends list. Thats how it is.

[Claire]

Anyone can deactivate their page. There is nothing to worry about that. Just do not add people you don't know and do not add random applications in your Facebook.