Final answer:
Tom Hanks co-starred with Julia Roberts in the films Charlie Wilson's War and Larry Crowne, both of which feature their strong on-screen chemistry.
Step-by-step explanation:
The actor who co-starred with Julia Roberts in the films Charlie Wilson's War and Larry Crowne is Tom Hanks. Both films were major Hollywood productions with notable performances. In Charlie Wilson's War (2007), Tom Hanks played the titular character, a U.S. Congressman, while Julia Roberts played the socialite Joanne Herring. In Larry Crowne (2011), Tom Hanks not only co-starred as the lead character Larry Crowne but also directed the film. Julia Roberts played the role of Mercedes Tainot, a community college professor. These collaborations between Tom Hanks and Julia Roberts showcase the chemistry between the two actors across different genres of cinema.