Who plays Richie Rich?

That depends on which version of Richie Rich you're referring to! There have been many actors who've played the character in different adaptations:

Live-Action:

* Macaulay Culkin played Richie Rich in the 1994 film.

* Jake Choi played Richie Rich in the 2015 TV series.

* Christian Convery played Richie Rich in the 2020 film.

Animated:

* David Kaufman voiced Richie Rich in the 1990s animated series.

* Alyson Stoner voiced Richie Rich in the 2004 animated series.

Other:

* Jackie Cooper played Richie Rich in the 1954 TV series, though this version was called "The Adventures of Jackie Cooper" and Richie Rich's character was simply called "Richie."

To clarify who you're asking about, you can specify which version of Richie Rich you're interested in (film, TV series, animated, etc.).