Eli David Marienthal (born March 6, 1986) is an American actor. He won the Annie Award for Outstanding Achievement for Voice Acting in a Feature Production for his vocal performance in the animated film The Iron Giant (1999).

Family and personal life
Marienthal was born in Santa Monica, California in 1986, the son of Penny Marienthal and Joseph Cross. He has two siblings, actors Harley Cross and Flora Cross. Marienthal is Jewish. In addition to acting, Marienthal has written and performed his own work as a poet, dancer, and playwright.

Marienthal graduated from the private East Bay French-American School in Berkeley, where all students learn to speak French and attend classes in two languages, and from Berkeley High School in 2004. He graduated magna cum laude from Brown University in 2008 with a double major in comparative literature and international development studies. He also holds a master's degree in development studies from Brown. As of February 2019, Marienthal is a doctoral candidate in geography at the University of California, Berkeley.