Johnny Galecki, born in Belgium in 1975 to American parents and raised near Chicago, was a child actor by the late eighties, playing Rusty in 'National Lampoon's Christmas Vacation' (1989) and later David Healy on 'Roseanne' (1992-1997). His defining role came as Leonard Hofstadter, the long-suffering experimental physicist of 'The Big Bang Theory' (2007-2019), the romantic and comic centre of one of the most-watched sitcoms of its era. Film credits include 'I Know What You Did Last Summer' (1997) and 'In Time' (2011). His register: exasperated decency with impeccable timing. Read more