Johan and Peewit - friends of the Smurfs
The original stars of the show!

Have you ever watched The Smurfs and thought, "Who are those two kids in the intro?". Starting in season two, the beginning of the theme song begins with two boys riding a horse and a goat into the scene. Those boys are Johan and Peewit, and they are the original stars of the show.
Johan was a sword-and-sorcery comic strip created by Peyo in 1947 and later evolved into Johan and Peewit with the introduction of Peewit (pronounced "Pee-wee"). The series followed the adventures of Johan, a young squire and aspiring knight, and his best friend Peewit, a court jester. Like most court jesters, Peewit is naturally funny and loves to entertain, but he also has a gluttonous side and is primarily motivated by food. Johan is a natural leader driven by nobility and a strong desire to do what's right, and his bravery is backed up by serious skills in swordfighting, archery, and all forms of combat.
Both boys worked in the court of the King, who remains unnamed even in The Smurfs. Johan and Peewit are sent on all sorts of missions and adventures for the King or to defend the innocent, which is how they meet the Smurfs.
The Smurfs were originally introduced as characters in the 1958 story The Flute with Six Smurfs, where Peewit finds and loses a magic flute, but the Smurfs offer to help make him a new one. After eleven years of Johan and Peewit as the stars, suddenly they were quickly eclipsed by the little blue guys. The Smurfs became incredibly popular while Johan and Peewit were neglected by their creator, whose focus was now on his newer and more popular characters.
In 1976, before the Hanna-Barbera cartoon was created, European animators made a Smurfs cartoon adaptation of The Flute with Six Smurfs, called The Smurfs and the Magic Flute. The cartoon mostly revolved around Johan and Peewit, with the Smurfs not appearing until 35 minutes into the movie. After the success of the first season of the Hanna-Barbera series, the movie was re-released and reminded everyone about Johan and Peewit.
The animators quickly included the two characters in season 2 of The Smurfs, beginning in the episode "The Cursed Country" where a dragon attacks the Smurf Forest and separates Smurfette and Hefty, who are kidnapped by a traveler who tries to sell them to the King. Johan and Peewit help free them and return them (and the other Smurfs) to Smurf Village. This begins a series of 19 episodes where Johan and Peewit befriend the Smurfs and help them on their adventures.
Despite the initial upstaging, Johan and Peewit become quite close with the Smurfs, even becoming the only humans trusted enough to find the Smurf Village. The Smurfs greatly benefit from having human allies and enjoy having friends from outside the village. Peewit even begins to introduce himself to strangers as "Peewit, friend of the Smurfs".
