Is there such a thing as a frameless sliding shower door?

The short answer is no. However, there is a give and take as to how frameless you can get. If you want a double slider, where both sides can slide open, you will need both a header and a bottom sill. There is no way around that. However, you may be able to get away with no side jambs or clear side jambs. If you only need one side to slide and the other side can be a fixed panel, you have more options. You won’t need side jambs at all. You will have the option to go headerless or go without a bottom threshold. If you opt to forgo the header there will still be a bottom door guide and vice versa. Using a header in favor of foregoing the bottom sill is generally preferred for tub enclosures. Folding shower doors are a great alternative to consider.