Mr. Holtenwasser was born in Germany. Sometime between his 20's and 40's, he was incarcerated in a concentration camp, during the holocaust, where many horrible things happened to him. Since the end of the holocaust, he has since moved to America, where he currently lives in the same neighborhood as The Murphy Family.
Most likely due to words getting twisted about his past, a playground rumor has the kids believing he is a Nazi and therefore are scared of him. Despite this, In "The Bleedin' in Sweden," Bill's magnet gets stuck to the numbers on Holtenwasser's house. When he reaches out to try and take it down for him, we can see the serial number tattooed on his arm. Bill thinks it is the number of people he's killed.
In "The Trough" he gives Kevin a ride home. He recounts to him how he's watched Kevin grow up throughout the years, seeing him playing around the neighborhood. He also mentions that he and his wife were the first homeowners in the subdivision. During this, Kevin notices a Star of David hanging from his rearview mirror but mistakes it for a pentagram. For this reason, Kevin (and later Bill) believe he is a Satan worshipper, even despite Frank's more accurate description of him as "a sad old man whose family was butchered in the war."
In "The Liar's Club," Holtenwasser joins Kevin and Frank and the rest of the neighborhood in the Murphy's basement, remarking he shared a basement with fourteen others in his lifetime. Vic likens this to a life of partying before Holtenwasser reflects it was, really, a very quiet life, "most of the time."
Otto Holtenwasser is a friendly elderly man, who is always generous to his neighbors and especially kind to children. Although 99% of the time, Otto managed to keep a delightful and carefree demeanor, he will occasionally have a sudden change in mood, and abruptly bring up a brief, but detailed event, of what happened to him, during the holocaust, often killing the cheery vibe, that surrounds him.
- The Bleedin' in Sweden
- Saturday, Bloody Saturday
- The Trough
- O Holy Moly Night
- Heavy Sledding
- The Liar's Club
- Night Shift
- This Is Not Good
- Mr. Murphy's Wild Ride
- Battle Of The Sexes
- Punch Drunk
- Mr. Holtenwasser drove Sue to the hospital for Maureen's birth, when Frank got caught up with other predicaments.
- His serial number is 721437.
- Despite being nice to most kids, he despises Jimmy Fitzsimmons, and he's not afraid to show his darker side and curse at him, when he's being bothered by him. In "This Is Not Good", he was happy when he overheard that Jimmy got sent to boot camp.
- In the third season, Mr. Hotlenwasser unintentionally gets roped into a fling with Ginny Throater, who was still recovering from her divorce at the time.