Star Trek: The Next Generation twice attempted to feature the Star Trek: The Original Series character Commander Pavel Chekov (Walter Koenig) alongside Lieutenant Worf (Michael Dorn) due to the characters' shared Russian heritage. As an orphaned Klingon child, Worf was raised on the farming colony Gault by his adoptive Russian parents Sergey and Helena Rozhenko. 100 years earlier, Pavel Chekov was born in Russia, and he served on the legendary USS Enterprise under Captain James T. Kirk (William Shatner).
As the adopted son of a Russian Starfleet officer, it's likely that Worf heard stories about Chekov's adventures on the Enterprise while growing up. This notion formed the basis of two potential storylines that would have brought Chekov into TNG and possibly even Star Trek: Deep Space Nine after Michael Dorn joined the cast as Worf in DS9 season 4. If the plans had been successful, Chekov would have joined Scotty (James Doohan), Spock (Leonard Nimoy), and McCoy (DeForest Kelly) in the ranks of TOS characters who reprised their roles for TNG. However, one potential Chekov story would have fundamentally changed the character.
