Alessandra Celletti is an Italian mathematician. She earned a master's degree in mathematics in 1984 at the University of Rome La Sapienza, and a PhD in 1989 at the Swiss Federal Institute of Technology in Zurich under the supervision of Jürgen Moser and Jörg Waldvogel. Her research activity concerns dynamical systems, Kolmogorov–Arnold–Moser theory, and celestial mechanics.
She is a founding member of the Italian Society of Celestial Mechanics and Astrodynamics, which she chaired from 2001 to 2013. Since 1993 she has coordinated the international CELMEC meetings. She is full professor of Mathematical Physics at the University of Rome Tor Vergata.
Since 2010 she has been an honorary "Celestial Mechanics Institute" member. Since 2016 she has been editor-in-chief of the journal Celestial Mechanics and Dynamical Astronomy. In 2012 she was an invited speaker at the 6th European Congress of Mathematics. In 2015 she was elected vice-President and in 2018 became President of the Scientific Committee in Celestial Mechanics of the International Astronomical Union. Since 2012 she has been a member of the Scientific Committee of the European Women in Mathematics.