Zack, a main character in The Freshman, The Sophomore, The Junior, and The Senior series, was a student at Hartfeld University and one of your character's roommates. He graduated in The Senior, Chapter 15. He makes his first appearance in The Freshman, Book 1, Chapter 2.
Zack has short, brown hair, blue eyes and light skin. In Book 1 through 3 he wears an olive green and beige jacket with leather flaps and pockets, white button up, and a blue shirt.
His formal wear is a purple tux with a blue and white plaid button up.
In Book 4, Zack wears a white button up ice cream patterned shirt.
Zack is a nice and sweet guy. He is seen to be very logical and idealistic but, most of all, he is extremely loyal to his friends.
Your Character and Zack appear to be very close. In fact, one might consider Zack to be Your Character's closest non-romantic relationship in the entire suite. The pair constantly dish out helpful advice to one another and share a fruitful dialogue from time to time.
If you helped to boost his confidence, in the last chapter of The Sophomore he will use new decorations for the party in the living room.
"Have I ever told you how adorably nerdy you are? Study buddies it is." - Zack to Tyler in Book 1, Chapter 5
Tyler is Zack's best friend and gaming partner.
"I've never felt this way about anyone else before... I don't want to lose what we have together!" - Zack about Brandon in Book 2, Chapter 14
In Book 1, Zack has a big crush on Brandon but hasn't got the courage to talk to him. Brandon finds Zack's shy behavior very cute and would like to get to know him better. If Your Character supports Zack, he'll make a move on Brandon and they'll go to the formal together. In Book 2, Brandon and Zack are an official couple and things seem to go pretty well, until Brandon confesses that he's transferring to a college in Peru for three months. Zack acts like it doesn't bother him much because he doesn't want to make Brandon worry. Privately, Zack is terrified because he doesn't know if he can handle a long distance relationship. In Book 3, it is shown how much they miss each other. Zack's roommates do everything to support the young couple and cheer them up. They are happy when Brandon comes back earlier at the end of the book. However, in Book 4, Zack reveals that he and Brandon broke up. They shortly see each other again at the Aurora Festival at the end of Book 4 before they both move on.
Grant is a worker that helps him and his friends work on Vasquez's house from being demolished. They begin dating at the end of The Sophomore, Book 2. When Grant's dog Burpy has gone missing and Zack asks Your Character to help him find it in The Senior, Chapter 10, he also mentions that he has planned a romantic surprise because it is the day of their one-year-anniversary since becoming official.
- Zack is shown on the cover of "The Freshman, Book 4" and "The Sophomore, Book 2".
- Zack makes a cameo appearance in The Haunting of Braidwood Manor, Chapter 6 and with Brandon in LoveHacks, Book 1, Chapter 15.
- In Helen Twombly's story within The Sophomore: Hartfeld Horror Story, he is renamed Jack and is the first to be killed by the Swamp Monster/Werewolf/Serial Killer.
- In The Sophomore, Book 1, Chapter 16, he decided to major in Architecture.
- If Your Character is single, he will ask you if you want to move in together at the end of The Sophomore, Book 2.
- It was revealed in The Junior, Book 1, Chapter 11, that the old abandoned building that Beau had burnt down was a project that Zack had taken on in hopes of renovating it for his architecture grant.
- Subsequently, it was also revealed that it was also an old Alpha Theta Mu clubhouse.
- He bears a resemblance to actor Jay Baruchel.
- Zack's last name was revealed in The Senior, Chapter 3 to be Zilberg.
- Coincidentally, he shares the same last name as Rachel Zilberg, one of the writers for The Freshman Series. 
- In The Senior, Chapter 15 he receives a Bachelor of Science degree with a major in Architecture.