Stage-trained performer who garnered wide critical acclaim (including a best actress award from the National Society of Film Critics) for her impassioned portrayal of drug-addicted, punk rock groupie Nancy Spungen in Alex Cox's "Sid and Nancy" (1986). Webb smoothly shifted gears to play Brian Dennehy's adulterous wife in Peter Greenaway's Pythagorean "The Belly of an Architect" (1987) and reached a wide audience as the girlfriend of Danny DeVito in the entertaining piece of Hollywood fluff, "Twins" (1988).