Being a "veggie" no longer means being an outsider in the Catalan capital.
You don't have to confine yourself to 100% veggie establishments to get the goods, either, as many standard Catalan eating spots offer a large choice of noncarnivorous platos.
Apart from the ubiquitous tortilla (made with eggs, Spanish-style, and not from cornmeal, Mexican-style), look for dishes like escalivada (grilled red and green pepper salad), berengenas al horno (eggplant/aubergine baked in the oven), calabaza guisada (stewed pumpkin), setas al jerez (mushrooms cooked in sherry), and pisto (Spain's answer to ratatouille). Jamón Serrano is not regarded as "real" meat in Spain and can appear in all sorts of dishes such as caldo (broth), so check with the waiter before you order.
Arabic, Indian, and Italian restaurants also serve vegetarian fare, with an inventive range of couscous, rice, and pasta-based dishes. If fish is an acceptable option, there are, of course, plenty of seafood restaurants to choose from, although these tend to be expensive.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.