La Pizzateca

There's only one vegan pizza but the have almost 8 different pizza for vegetarian as well and you can order anyone without cheese.

They have one vegan pizza, it doesn't have cheese but is perfectly delicious without. It costs €1 for each additional topping - staff were very friendly and the service was fast!

Finally a vegan pizza available and properly marked in the menu. They don't add any vegan cheese, but the pizza is so delicious that trust me, you won't miss it. Plus you can add some extra veggies to make it ever tastier. They've recently moved to a larger premises in the same street (c/León, 35), just a few meters away and opposite the previous location. Still very take-out orientated but there are several tables at the back, so you can now eat-in as well.

It's possible to eat vegan while vacationing in Spain but be prepared to eat the same thing over & over and to annoy plenty of waiters who don't seem to be used to questions of food ingredients.
So, this place was a relief! The man behind the counter knew what vegan was and there is one vegan option on the menu. None of the ready made slices were vegan (some were vegetarian) but ordering the whole pizza was not overly large or expensive.
Service was fast and pleasant. Be aware - this is a walk-in pizza place with only about 4 seats along a counter and no available bathrooms.