 Dench alizaliwa mjini Heworth, York, North Riding of Yorkshire, akiwa kama binti wa Eleanora Olave aliyekuwa Jones, mzaliwa wa Dublin, na Reginald Arthur Dench, daktari aliyekutana na mamake Judi wakati anasomea masuala ya afya katika Chuo cha Trinity cha mjini Dublin. 