Arnold (Hey Arnold!) - Last Name

Last Name

Arnold's last name has never been revealed on the show. With the exception of a few secondary characters (including Sid and Brainy), the only other notable characters whose surnames are unknown are Arnold's grandparents. They presumably have the same last name as Arnold, since in "Parents Day" and "The Journal" it is revealed they are his father's parents. The mystery surrounding Arnold's full name became a running gag on the show, by the last name almost being revealed, then someone or something interrupting or otherwise preventing it from being heard. Some notable occasions when the name is almost revealed include:

• In a commercial for the show that aired in the early part of the show's run, Arnold talks to the viewer to straighten out some facts about himself (such as the revelation that his notable red outerwear is a shirt, not a skirt). He ends with, "And yes, I do have a last name. It's..." at which point the screen turns into static and the sound cuts off, because the camera's batteries run out.
• In the episode "Fighting Families" Arnold wins the school's raffle drawing for the chance to be on the game show Fighting Families. The lady doing the drawing announces, "The winner is Arnold...hm, there seems to be a smudge over the last name." Here it is revealed that Arnold is the only one in the school with this first name, thus making his surname somewhat unnecessary.
• A similar instance to the one above occurs in "Eugene, Eugene!", where Tim Curry's character is casting the school kids for an upcoming play, and says, "I can't read my own handwriting", when he's casting Arnold as the villain. However, that scene did at least reveal Lila's last name (Sawyer, as mentioned above).
• In one episode, "Crush on Teacher", in which Helga does one of her many passionate monologues about her love for Arnold, she says that she would one day like to become "Mrs.Arnold...wait, what is his last name?", revealing that she is just as clueless as the viewer.
• In the episode "The Journal", Phil is reading the part of Miles's journal that recounts his and Stella's wedding. He gets to the part when they are pronounced "Mr. and Mrs...." at which point Grandma interrupts with a loud burp.
• In the episode "Married", Helga dreams that she is married to Arnold, and that she is the President. In her opening speech, she introduces Arnold as "Arnold Pataki."
• Series creator Craig Bartlett had been planning to finally reveal his last name in a second Feature film for the series, which would also deal with his search to find his parents. Craig mentioned in a subsequent online chat: "I had an idea for the Jungle Movie (how Bartlett refers to the planned film), in the opening scene, a man comes to the door of the boarding house, and Arnold signs his name. Right, that's how you find out." However, problems between Bartlett and Nickelodeon, as well as the low gross of the first film, led to the cancellation of this second film.

In 2006 in an online chat with Hey Arnold! fans, Bartlett revealed that Arnold's grandpa used his last name throughout the series, heavily implying, but not confirming, that Arnold's last name is "Shortman" (a transcript of this chat can be found here). Craig also mentioned that Arnold's second name most likely is "Phillip".

• In some episodes, other characters can be seen referring to Arnold as "Shortman" (In the beginning of Arnold Visits Arnie, Helga is telling the other characters their positions in a game of baseball she is quoted saying "Looks like you're on Shortstop, Shortman.")
• In a commercial for Hey Arnold, where Bartlett is interviewed, Bartlett promises that Arnold's last name will be revealed, and that the audience has been hearing his name throughout the entire series. Grandpa frequently calls Arnold "Shortman."