Most popular computer codes for calculating model stellar and planetary atmospheres are briefly reviewed. A particular emphasis is devoted to our universal computer program Tlusty (model stellar atmospheres and accretion disks), CoolTlusty (a variant of Tlusty for computing model atmospheres of substellar-mass objects such as giant planets and brown dwarfs), and Synspec (an associated spectrum synthesis code). We show the highlights of actual applications of these codes which include extensive

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... rids of fully line-blanketed non-LTE model atmospheres of O and B stars, and grids of model atmospheres of extrasolar giant planets and L and T dwarfs.