Krillin is Goku's best friend who had grown up with him through the course of the original Dragon Ball series. He is an incredibly strong human but later in the series he plays less and less of a fighting role as the Saiyans and other characters far surpass his strength. While originally thought naturally bald, he reveals later in the Dragon Ball Z series that he had kept his head shaved. After marrying Android 18 he let it grow out again, revealing naturally straight black hair.
After his marriage to Android 18, the two have a daughter, Marron. While he had been facing a steady decline of relevance in the series (in Dragon Ball, he was one of Goku's most important allies, in Dragon Ball Z he plays important roles in the Saiyan and Frieza sagas, but his relationship with 18 is his only real important plot point by the time of the Android/Cell saga), this marks the point at which he "settles" down, so to speak, becoming much less involved in the fighting.
He does indeed hold the record for being killed the most times, in Dragon Ball he was killed by Tambourine, one of King Piccolo's henchmen, and in Dragon Ball Z he was killed by both Frieza (he was impaled) and Majin Buu (he was eaten). In Dragon Ball GT he was killed by Android 17, there are probably a few other times, but you get the idea.
Krillin is a very short man (no bigger than a child) originally seen bald, but with naturally black hair . He has six dots on his head (likely from incense burns, as he used to be a monk) and no nose (he was able to defeat Bacterian during the Tenkaichi Budoukai because he didn't have a nose). He is quite muscular as he is one of, if not the
strongest human in the Dragon Ball Z series. He is usually seen in a similar orange and blue outfit to Goku's, but has also been seen in Saiyan Armor
and other outfits.