Stu is the responsible, uptight, worried, a coward, and wimpy member of the Wolfpack. He is a dentist but refers to himself as a doctor. Stu really doesn't drink that much, apart from vodka. He is the most crazy out of the Wolfpack during their drunken nights. Stu was once beaten by his ex-girlfriend, Melissa, who also cheated on him with a bartender, and was still together with her despite knowing this. Stu finally had the guts to stand up and break up with Melissa at Doug and Tracy's wedding. One time when he was drunk, he even pulled out his own tooth to win a bet against Alan who betted Stu that he wasn't a good enough dentist to be able to pull out his tooth and even he got married to a stripper named Jade, then later made a date with her.
Two years later, Stu really has become uptight and selfish about his wedding in Thailand and how the bachelor party is going, as he and the guys are going to Thailand, but Stu didn't want to invite Alan, but Doug talks him into it. Stu tells the guys at an iHop that he is going to have a bachelor brunch, with just chococlate chip pancakes, lap dance from the waitress and no alcohol. Stu really becomes happy with Lauren. He didn't even want to go with the guys down to the beach to get a beer, but he decided a little fun couldn't hurt. While drunk, Stu got a tattoo (which was a copy of Mike Tyson's), he yelled and cryed like a baby while he got it, and later had anal sex with a transsexual. He wouldn't leave Bangkok until he found his brother-in-law, Teddy. He finds him in time for his wedding. Stu shows Lauren's father that he may sometimes be an uptight nerd or coward, but he has a demon in him which reveals itself in his drunken state. Stu then got married to Lauren.
Two years later after the events in Bangkok, Stu is still friends with Phil, Doug, and Alan, he got the tattoo removed from his face, and got checked due to the anal sex with Kimmy. Stu also goes along for the trip to bring Alan to New Horizons. Only for him to get involved on another adventure with Phil and Alan as Stu hasn't really learned anything from their past two adventures in Las Vegas and Bangkok. Along the way, Stu tells Phil that New Horizons isn't going to help Alan or any other rehab cause all he has is Phil, Stu, and Doug. While Phil and Alan try to capture Chow, Stu stands by the limo waiting only to chase after Chow until Chow hits the limo, Stu then puts Chow in the trunk. At the end of the film, Stu wakes up with breast implants only for him to freak out and have the monkey from the previous film drop on his shoulder.
Stu and Doug are best friends and have known one another since childhood. They are both the more sensible and reasonable half of The Wolfpack when compared to the wild and rebellious behaviour of both Alan and Phil. They are both horrified when Alan risks their safety by tricking Doug into ramming the side of a truck while Alan and Phil both share a laugh over it, and are both in agreement that Alan should have deleted the photographic evidence of their drunken night in Las Vegas as promised, whilst Phil is amused and just laughs it off.
Stu and Phil are both very close friends, having known each other since childhood. Despite their contrasting personalities and Phil's tendencies to embarrass and steal from Stu, they both genuinely care for each other.
Stu's relationship with Alan has never been easy. They had met before the bachelor party for Doug in Las Vegas and Stu didn't mind Alan for the most part, although he is the one who is most annoyed by Alan's stupidity. Upon learning that Alan drugged their drinks, Stu is outraged and has nothing but insults and disdain for Alan, though he is still occasionally kind and friendly towards him. Due to what happened in Vegas, Stu does not want Alan at his wedding out of fear that he may drug him again, but reluctantly invites him after insistence from Doug and Phil. Despite his initial reluctance, he becomes glad that Alan came along, but is again furious when Alan confesses to spicing the marshmellows they had with muscle relaxers and ADHD medication the night before Stu's wedding, although he intended to drug only Teddy, so the rest of them could enjoy the weekend without him. Stu forgives Alan when he realises that their rescuing Teddy from Bangkok has impressed his fiance Lauren's father enough to accept both him and his marriage to Lauren, and is extremely grateful to Alan for having Mike Tyson perform a musical show for him as a wedding gift. In the third film, Alan has become rude to Stu but they are still friends.
- Missing front tooth
- Tased in the neck at point-blank range by police taser gun
- Bleeding mouth
- Vomiting from blood
- Hit in the stomach with a crowbar by Mr. Chow
- Tattoo on the left side of face (just like Mike Tyson's)
- Hit with a stick by a monk for talking.
- Anal sex with a transexual
- Accidentally covered in pig blood by Chow, resulting in shock
- Breast implants
- Got a slight cut in the neck by Chow
- Attacked by chicken
- Attacked by the monkey
"Rogaine: check. Using of the Rogaine: check."
"It's okay, everything's gonna be okay.... WHAT THE FUCK IS GOING ON?!?"
"I lost a tooth, I married a whore."
(to Alan) "You are literally too stupid to insult."
"I look like a nerdy hillbilly."
"You're a such a FUCKING MORON!"
"What the Fuck is Going On?!?"
"This is a Real Tattoo!"
"What did you do, Alan?!"
"You're the Bearded Devil!!!"
"WHOOOO! FUCK THE POLICE! FUCK THE POLICE!"
"I'm not going back without Teddy."
"I made love, to a man with Boobies"
"YOU DRUGGED US AGAIN???!!!"
"I'm Trying!!!Slow Down!!!"
"That's my face, go go go..Nice work,Alan"
"I have boobies now!"
"I told himself I would never come back"
"ARE YOU OUT OF YOUR MIND???!!!"
- In the original script for The Hangover, Stu was to have already been married and had two kids but that was used for Bradley Cooper's character, Phil instead.
- In the third film, Stu had different seeing glasses from the last two films.
- Ed Helms had to take leave from The Office while filming The Hangover 3. His character was written on a boat travelling in the sea for the next while.