Valentina Sierra (also known by the stage names Cataleya Dark, Kitty Monroe, Stela, Petra, and others) is a Czech adult film actress born on March 25, 1977, in Prague (Czech Republic). She began her professional career in 2017 at the age of about 40 (although she had appeared in a limited number of productions previously) and remains active to this day. She specializes in MILF, hardcore, anal, fetish, and extreme scenes for studios such as LegalPorno, Public Agent, Perverse Family, Score Group, and others. She was nominated for a Czech Erotic Award in the Best MILF category (2019).