@agenthanh said:
How to fetch tv shows of an actor by person id?
I found out that you can fetch movies by 'discover/movie' with the 'with_people' query but it's not the same thing for 'discover/tv'.
There's no 'with_people' query string in the 'discover/tv' api

You can search directly by person ID.
https://developers.themoviedb.org/3/people/get-person-details
Examples with Mark Harmon
https://www.themoviedb.org/person/19728-mark-harmon

https://api.themoviedb.org/3/person/19728?api_key=THE_KEY&language=en-US&append_to_response=movie_credits
https://api.themoviedb.org/3/person/19728?api_key=THE_KEY&language=en-US&append_to_response=tv_credits
https://api.themoviedb.org/3/person/19728?api_key=THE_KEY&language=en-US&append_to_response=combined_credits

There are plans to add this feature.
It's already on Trello's To-Do list.
https://trello.com/c/nP2gJ8eH/38-add-withcast-withcrew-filters-to-tv-discover
There is no implementation deadline.
You can vote. More votes, faster. :-)