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.
In addition to this, many products come preinstalled as bloatware. McAfee products (amongst a hoard of other programs) have come preinstalled on Windows laptops I've purchased from Dell and Lenovo.
The "Fresh Start" feature in newer builds of Windows 10 (1709-onwards if I'm not mistaken) will automatically remove these kinds of applications preinstalled on new systems.
Excellent feature in itself, but also a cludge around a broken economic system. OEMs shouldn't be prioritizing their profits at the expense of the users their business exists for.