McTavish was a Human woman, the great aunt of Montgomery Scott in the 23rd century.
In 2269, Scott used his great aunt's haggis as an epitaph when he spotted a new computer being constructed within the computer core of the USS Enterprise. Systems had been overridden by the Master Computer of the Amusement Park planet. (TAS - Log Three novelization: Once Upon a Planet)
Scott mentioned her and her haggis again while observing the unusual variety of starships trapped in the Delta Triangle, including the SS Bonaventure and another vessel with a hull made from a highly-dense celluloid wood. (TAS - Log Four novelization: The Time Trap)