Anti viruses are typical bundleware installed when installing 'free' software. If you don't look carefully, when you click, 'i agree,' you'll get a bunch of other software you don't want.

Some crazy software companies then used a dark pattern - clicking 'I don't agree,' meant you agreed to install unwanted crap.

Adobe flash, Java runtime, utorrent and any installer from cnet.com are examples. That's why I installed Unchecky to protect me from bundleware and automatically uncheck, skip 'offerings' when installing new software.

Edit: As mentioned below, the Chrome team used bundleware extensively in its early days.