People that aren't on my friends list showing up in chat bar?

[Budgie]

Recently, as in the past week or so, people who are not on my friends list are showing up in my chat bar. I only keep close friends and family on Facebook, so I can see everyone at once. I noticed the list was really long and I see five or more people that I am not friends with, on my chat bar. Does anyone know why this is? I do not have special lists for my friends or anything. At first I thought it was people I had recently viewed, but I very rarely do that and some people I haven't looked at.
Are these people looking at my profile?
Also, from what I can tell, they are all people I used to be friends with a year or more ago.

[Rayan]

If you have just searched them, this would be friends of friends.

[Jacob]

i agree with previous answer.