* The name is misspelled or slightly different. Double-check the spelling and try searching for variations of the name.
* He may be a relatively unknown actor. Smaller roles and independent productions may not have extensive online databases.
* He is not a public figure. Perhaps the individual is not involved in film or television.
If you have more context, such as a specific film or show he may have been in, or a time period he was active, it could help narrow down the search.