Smith tied the knot to actor Robert Stephens, and they welcomed two sons, Chris Larkin and Toby Stephens, into their family. Both pursued careers in acting, continuing the legacy established by their mother.
Following her divorce from Stephens, Smith entered into marriage with playwright Beverley Cross, who had proposed to her many years prior. Cross’s death in 1998 left Smith heartbroken and profoundly impacted.

Her grief was widely acknowledged, with Smith once stating, “They say it goes away, but it doesn’t… it just gets different.” She continued to keep her life under wraps even following the tragedy.
Despite her intense privacy, Smith’s influence on the world of cinema and theater was unmistakable. She gained global recognition through her performances in “Harry Potter” and “Downton Abbey” as her career grew.