Sadie is short and heavyset, with curly blonde hair. She works at the Big Donut, so she's usually seen wearing the uniform. Her uniform consists of a periwinkle polo underneath a purple shirt, which is displaying the Big Donut logo (the half-eaten doughnut). She wears black leggings and pink-red shoes. Her casual outfit is a dull pink jacket, green shirt, black leggings, and pink-red shoes. In "Coach Steven", she wore a periwinkle tank top with pale red short sweatpants, red flat pumps and the back of her hair is in a ponytail. In "Island Adventure", she wore a black shirt, then few days later, she wear Lars's shirt that has a snake picture on it. In "Watermelon Steven", she wore a blue shirt, blue skirt, red skinny low-pumps and she had a purple-brown purse.
Sadie is a clerk at the Big Donut and works with Lars. She is friends with Steven and enjoys his comebacks. Although she is friends with Lars, she doesn't like it when he makes fun of Steven. As shown in "So Many Birthdays" and "Island Adventure" she is physically capable of protecting herself and loved ones if needed. She is often empathetic of Steven, usually contrasting Lars.
Sadie has a crush on Lars, as confirmed in "Joking Victim" but he is unaware of it. At times Lars can be a jerk to Sadie and be lazy, snobbish and rude towards her. In "Island Adventure", he kissed and cuddled with Sadie. Though the two constantly go through a love/hate relationship (Steven once called them "married") they are shown to be good friends and are almost always seen to do things together as shown in "Tiger Millionaire" and at the end of "Steven and the Stevens" at the Beach city Palooza. Lars is seen to get jealous over Sadie, as in "Horror Club" he attempts to one-up Ronaldo Fryman after he is seen "flirting" with Sadie.
- "Gem Glow"
- "Laser Light Cannon" (non-speaking cameo)
- "Cat Fingers"
- "Bubble Buddies"
- "Tiger Millionaire"
- "So Many Birthdays"
- "Rose's Room" (room's magic)
- "Mirror Gem"
- "Ocean Gem"
- "Watermelon Steven"
- "Lion 3: Straight to Video"
- "Alone Together"
- "Future Vision"
- "Marble Madness" (mentioned)
- "Political Power"
- "Shirt Club"
- "The Return (non-speaking cameo)
- "Full Disclosure (episode) (non-speaking cameo)
- "Say Uncle" (non-speaking cameo)
- Along with her co-worker Lars, Sadie is one of the first entirely human characters in either the pilot or main series.
- Rebecca Sugar has confirmed that Sadie likes to eat oyster crackers, which is shown in "Joking Victim".
- In "Coach Steven", Sadie is shown writing in her journal using her left hand, which reveals that she could be left handed.
- Sadie and Lars were confirmed by Rebecca Sugar to be some of her first ever characters. "Lars and Sadie were old characters of mine, from college!" - Rebecca Sugar on Reddit.
- It has been heavily implied and later confirmed that Sadie has a crush on Lars.
- Sadie's voice actor is Kate Micucci, a singer and songwriter.
- Sadie states in "Joking Victim", that her job at the Big Donut started as a summer job, but that it has been two years prior to the date.
- Sadie is the first fully human character so far to single-handedly defeat a Gem creature.
- When Sadie appeared in "Watermelon Steven", she had the same scar she got in the episode "Island Adventure". This detail is carried on to most of the episodes seen after said events.
- It is revealed in "Lion 3: Straight to Video" that Sadie's mom still packs her lunches.
- In "Island Adventure", Lars made the first move and kissed Sadie.
- Lars may be jealous of Sadie's friendship with Ronaldo, as shown in "Horror Club".