This paper presents the 12th edition of a catalog of quasars and active galactic nuclei (AGN). The catalog includes 85,221 quasars, 1,122 BL Lac objects, and 21,737 active galaxies, including 9,628 Seyfert 1s, almost doubling the number from the 11th edition. It also lists all known lensed and double quasars. The catalog provides position, redshift, photometry (U, B, V), and 20 cm flux densities for each object. The absolute magnitude is given for each object, along with 20 and 6 cm flux densities when available. The catalog is not complete but aims to be a comprehensive survey of the literature. The catalog defines quasars as star-like objects with broad emission lines and brighter than M_B = -23. AGN include Seyfert 1s, Seyfert 2s, and LINERs. The catalog includes classifications such as S1.0, S1.2, S1.5, S1.8, S1.9, S1i, S1h, S1n, S2, Q2, S3, S3b, S3h, S, S?, and H2. The catalog also includes information on redshift, photometry, and absolute magnitude. The catalog is used for reference and not for statistical analysis. The catalog includes references to various surveys and data sources. The catalog is a compilation of all known quasars, BL Lac objects, and Seyfert 1s. The catalog is a valuable resource for researchers in the field of quasars and AGN.This paper presents the 12th edition of a catalog of quasars and active galactic nuclei (AGN). The catalog includes 85,221 quasars, 1,122 BL Lac objects, and 21,737 active galaxies, including 9,628 Seyfert 1s, almost doubling the number from the 11th edition. It also lists all known lensed and double quasars. The catalog provides position, redshift, photometry (U, B, V), and 20 cm flux densities for each object. The absolute magnitude is given for each object, along with 20 and 6 cm flux densities when available. The catalog is not complete but aims to be a comprehensive survey of the literature. The catalog defines quasars as star-like objects with broad emission lines and brighter than M_B = -23. AGN include Seyfert 1s, Seyfert 2s, and LINERs. The catalog includes classifications such as S1.0, S1.2, S1.5, S1.8, S1.9, S1i, S1h, S1n, S2, Q2, S3, S3b, S3h, S, S?, and H2. The catalog also includes information on redshift, photometry, and absolute magnitude. The catalog is used for reference and not for statistical analysis. The catalog includes references to various surveys and data sources. The catalog is a compilation of all known quasars, BL Lac objects, and Seyfert 1s. The catalog is a valuable resource for researchers in the field of quasars and AGN.