All is fair in the Dick Wolf universe, including character crossovers and actors popping up on more than one series at a time.

After getting his start as a writer on Hill Street Blues in 1985, Wolf to superstardom when he created Law & Order in 1990. He has since helmed multiple Law & Order spinoffs, including Law & Order: Special Victims Unit, which premiered in 1999.

Wolf transported viewers from New York City to Chicago in 2012 with the creation of Chicago Fire. Its spinoffs include Chicago P.D., Chicago Med and Chicago Justice.

Just when fans thought Wolf couldn’t possibly have any more procedural drama ideas up his sleeves, he masterminded the FBI universe, made up of FBI, FBI: Most Wanted and FBI: International.

Over the years, eagle-eyed fans may have noticed that Wolf has a few favorite actors who have turned up on his series time and again — not including the full-show crossovers within the One Chicago and FBI universes.

Scroll down to see which actors have taken their character from one franchise to another — and which stars have played more than one role for Wolf: