Genma Shiranui

becomes the proctor during final rounds of the Chunin Exams after the death of Hayate Gekko. He usually has a senbon in his mouth.

Chunin Exams arc
After Hayate's death, Genma referees the final round matches of the Chunin Exams. He battles Baki during Orochimaru's attempted invasion of Konoha. However, their fight is interrupted when Orochimaru calls off the invasion.

Search for Tsunade arc
Later, in the anime, he and Aoba are assigned to announce Tsunade's inauguration as the Fifth Hokage.

Sasuke Retrieval arc
Genma is returning to the village from a mission with Raido Namiashi, Iwashi Tatami and Shizune, when he and Raidou encounter the Sound Four. In order to defeat Raido and Genma, the Sound Four activate level two of their cursed seals, leaving Genma gravely injured and in serious need of medical attention. In addition to this, Genma and Raido barely had any chakra left.

Rescue Gaara arc
Genma appears along with Naruto's loved ones on the right at the very end beside Anko in his dream where he gives his hand out to Gaara after he is revived by Chiyo

Fire Temple arc
Genma's Part II debut is in this arc where he is seen giving out orders to some Chunin during Furido's attack on the village.

Pains Invasion arc
Later, Genma appears with Yamato and other Jonin helping to restore the village after Pain and Naruto's fight.

Abilities
Despite the handful of fights he has been in, Genma has yet to be seen in combat. He can spit the senbon from his mouth as a projectile with enough force to deflect a kunai. Given that the Sound Four needed to activate their cursed seals in order to defeat him, it is likely that he is a formidable fighter.

Trivia

 * Genma said during the Chunin Exams that Naruto has a 'mean left hook'. But during that time, Naruto did an uppercut, not a left hook.