What animal start with letter r in Spanish?

No true Spanish Words use the letter K. The K sound would be spelled with a C (before A, O, U, or a consonant) or with QU (before I or E).

A Word with a K might show up in Spanish writing but it would be, from the Spanish viewpoint, a foreign Word. It would be like using "cañón" in English writing a using the N with a tilde and the O with a written accent.