The following is not a 100% guaranteed method, and should not at all be attempted for scripting. But some times it is good enough for quick interactive shell usage. A file file glob like
[abc]*
(which will match all files with names starting with a, b or c) can be negated by inserting a "^" character first, i.e.
[^abc]*
I sometimes use this for not matching the "lost+found" directory, like for instance:
mv /mnt/usbdisk/[^l]* /home/user/stuff/.
Of course if there are other files starting with l I have to process those afterwards.