Olga resembles her mother more than she resembles Big Bob. Although, she has her mother's blond hair and skin, she had her father's nose. Her hair is style in that of a flip bob cut style and she wears a black headband. Her usual outfit is a cropped white long-sleeved shirt with a black vest over it. She also wears a green plaid skirt and green hoop earrings, as well as brown boots and white knee-high socks.
In Student Teacher, she appears to be wearing lipstick or lip gloss as her lips are quite visible, as well as a beret, and a black long-sleeved shirt, and a longer version of her plaid skirt
In Hey Arnold: The Jungle Movie, nothing much has changed in her appearance. However, during the trip, she wears a purple/indigo striped tank top with white frilly lacy on the bottom. She also dons denim shorts, purple hoop earrings, violet headband, and navy blue sneakers with white laces and soles. She also has a pair of blue cat-eye sunglasses
In her younger days, she had a unibrow just like Bob.
Olga is Helga's older sister. Although it's never said how far apart in age they are, from what's said in Helga on the Couch, she must be at least 11 years older than Helga. Olga is very intelligent (she has not received so much as an A-minus since third grade), beautiful, popular, talented, sweet, well-meaning, and kind. Despite her intelligence, she appears quite airheaded when it comes to Helga's feelings and never seems to realize that Helga doesn't like her at all.
It is apparent that she suffers from perfectionism and is known to become easily depressed when she doesn't meet her own high expectations. In "Olga Comes Home", she locked herself in her bedroom and cried for days when she thought she got a "B+". Unbeknownst to Olga, however, Helga had intercepted her sister’s college report card and changed the grade out of jealousy. Near the end of the episode, Helga confesses to Olga what she did, and the sisters reconcile (at least until Olga’s next appearance).
Despite her seemingly perfect exterior, however, Olga suffers just as much, if not more so, under their parents than her sister. While she isn't neglected and unloved like Helga generally is, Olga feels overburdened and pressured by their constant praise and expectations of her---Olga even goes so far as to describe herself as a "wind-up doll," and claims that Helga's lucky that their parents aren't breathing down her neck all the time, expecting nothing short of perfection.
Throughout the series, Olga (who has good intentions) tries very much to bond with Helga. But it usually doesn't work because Helga despises Olga and is very jealous of the attention that Olga receives from their parents and of her perfectionism. From Helga's point of view, Olga's insincere. Olga has a tendency to pay attention only to the good in life and ignores the negative as well as (albeit unintentionally) be condescending to Helga. She does not really listen to Helga's bigger concerns about the family dynamics. Except for the episodes "Olga Comes Home," where Olga mentions the stressful demands put upon her from their parents and Student Teacher where Helga tells Olga that it would be better if Olga give her some space, only the surface is scratched. But the root of their problems are never really dealt with. Throughout the series, the sibling relationship is primarily through Helga's point of view.
Olga and Helga's Relationship
There are a few instances where it's shown that Helga really does care about Olga. The episodes include as follows:
Helga's amused by the idea of Olga marrying a seemingly sociopathic con man and pathological liar named Doug LeSham because that would mean that Olga would fall from grace with their parents. Doug very quickly wins over Bob and Miriam with his clever lying. But on the day of Olga's wedding, Helga catches Doug talking to another woman on the phone and knows that he is not faithful. Helga confronts Doug and begins intervening on Olga's behalf.
She threatens to press the redial button to spill the news of his marriage to the other woman. Doug panics and Helga tells him to leave, basically saying that she'll tie up the loose ends. Upon hearing that, Doug leaves. Helga then writes a note to Olga and signs it with Doug's name saying that he got called away on an emergency.
Olga comes home for spring break and surprises Helga when she shows up at her school, P.S. 118, and announces that she decided not to move to Alaska but to instead be the new student teacher for Helga's class. Throughout most of the episode, Helga tries to get Olga into trouble and at one point, gives Olga's car a flat tire. But Helga becomes angry when Olga meets her on the bus and tells her about her flat tire which she doesn't know was done by Helga. After Olga goes too far and reveals to the class that Helga was a bedwetter until the age of 7 and after Arnold persuades Helga to have a sit down with her sister, Helga confronts Olga.
She tells a surprised and perplexed Olga that it is not working out. She persuades Olga to become a student teacher at a school in Alaska, claiming that the further apart in distance that they are, the closer they'll be emotionally---Olga complies. At the very end of the episode, Helga is writing a letter in response to the one that she received from Olga. Initially Helga signs it with the word "From" but then looks at a picture of Olga and crosses out from and signs "Love, Helga".
Helga's initially delighted by the fact that Olga joined the Big Sisters, Big Brothers program because she knows that Olga will be busy entertaining someone else and will leave her alone. But when Helga finds out that Olga will be spending time with Lila, Helga becomes jealous and does everything she can think of to mess things up.
Near the end of the episode, Helga admits to Olga that she's jealous of how madly in love she and Lila are, thinking it's better than the relationship Olga has with her. Olga reassures Helga by telling her that she'll always be her "baby sis" and that they have a bond only real sisters can have and nobody will ever break.
- During the flashback in "Helga on the Couch", Miriam says Olga is 15 years old, while Helga is in preschool and is most likely 3-4 years old. Therefore, Olga is approximately 11–12 years older than Helga, and is around 20-21 years old in the series.
- In one episode, Helga says Olga attends Bennington College but it's revealed in Season 1 on Olga's report card that she goes to Wellington College. However, there is an existing Bennington College located within the United States in the state of Vermont, and there is an existing Wellington College in the country of England.
- Her tears are black because of her mascara. It is unknown if she wears any other makeup, however, in "Student Teacher", she did wear lipstick.
- In the episode "Helga on the Couch", Olga's able to play Chopin's 'Minute Waltz' in exactly one minute---an impossible feat in real life, no matter how talented one is at playing the piano.
- Olga and Lila exhibit similar personalities in the episode "Big Sis". It was during that episode that Olga became Lila's "adopted big sister".
- In the episode "Phoebe Takes the Fall" it was explained by Big Bob that Olga was unable to win the Trivia Question for the state bird of Maine, the chickadee. It stated that was the only trophy that Olga couldn't win.
- Olga drives a pink 1974 Volkswagen Karmann Ghia convertible with flowers on it.
- 14a. Spelling Bee (mentioned)
- 15a. Olga Comes Home (first full appearance)
- 20. Arnold's Christmas (cameo, first appearance)
- 37b. Quantity Time (mentioned and shown in pictures)
- 41a. The Aptitude Test (mentioned)
- 43b. Olga Gets Engaged
- 51a. Phoebe Takes the Fall (mentioned)
- 56. Arnold's Thanksgiving
- 63b. Student Teacher
- 78. Helga on the Couch (flashbacks)
- 81b. Big Sis
- 95b. Big Bob's Crisis
- Hey Arnold! The Jungle Movie