Yes, but it might require some effort. 

If you boot from an operating system installed in a different drive or partition than your "forked up" operating system, the fork bomb will not be triggered. You can then edit the file in your "forked up" operating system which specifies which programs run at at startup to remove the fork bomb program. You will then be able to boot into your formerly "forked up" partition with no problems. The file or files you have to edit vary by operating system. And the technique for looking at and editing the files in the "forked up" operating system partition from the other operating system varies.

Some operating systems also allow you to boot while disabling some of the programs that run on startup, though the method for doing this also varies. 

Another option could be booting from another operating system, copying out all the files you want to save, then wiping your "forked up" operating system partition or drive and installing a new operating system; this would also completely remove the fork bomb.  If you're curious, I can give more specific advice pertaining to removing a fork bomb from a specific operating system.
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