Andres Saag (born 21 November 1955) is an Estonian mycologist.
He has recombined the following taxon: Nephromopsis yunnanensis <small>(Nyl.) Randlane & Saag, 1992</small>.
His publications include Eesti puudel kasvavad suursamblikud (Epiphytic macrolichens of Estonia), Eesti kividel kasvavad suursamblikud (Epilithic macrolichens of Estonia) and Eesti maapinna suursamblikud (Epigeic macrolichens of Estonia), all co-authored with Tiina Randlane and Ljudmilla Martin.