In theory I guess there could be 'unlimited' scales. Although when it comes to playing music from western culture there are only very few that come up:

The Major scale and it's modes

The Melodic Minor scale and it's modes

The Harmonic Minor scale and it's modes

The major and minor pentatonic scales (these come from the major scale) and blues scale

The diminished, augmented and whole tone scales.

The chromatic scale.

If you are interesting in playing music from other cultures I'm certain you will find other scales, as well as ones that do not correspond with our 12 tone system.