Simone Luna Louise Söderlund Giertz (/ˈjɛtʃ/ YETCH; Swedish: [ˈjæʈːʂ]; born November 1, 1990) is a Swedish inventor, maker, robotics enthusiast, TV host, and professional YouTuber.

Simone Luna Louise Söderlund Giertz was born on November 1, 1990, the youngest of three siblings. Her mother is television host Caroline Giertz, who worked on reality television programs about ghost hunting, and her father worked as a television producer. She was raised in a middle-class household in Saltsjö-Duvnäs [sv], Sweden (near Stockholm). Giertz is a descendant of Lars Magnus Ericsson, founder of Ericsson.

In elementary school, Giertz was interested in woodworking. She named the Disney cartoon character Gyro Gearloose as one of her earliest inspirations.

At the age of 16, Giertz spent a year in China as an exchange student. She stayed in Hefei, where she learned basic Mandarin. During her stay, she also made an appearance on a Chinese sitcom. Her parents got divorced while she was in China, which she was informed of the day she returned. Three months later, she enrolled in a Swedish boarding school in Nairobi, where she learned Swahili. After graduating from high school, she returned to China, spending six months in Nanhai, Guangdong. Giertz studied physics at the KTH Royal Institute of Technology, a research university in Stockholm, but dropped out after a year. In 2012, she became an editor for Sweden's official website, working on the Chinese-language version.

Giertz was self-taught in robotics; her interest in electronics began in 2013, when she attended a friend's talk about hacking hardware. The same year, she began studying advertising at a vocational school. To fulfill a curriculum requirement, she had an internship in San Francisco as a product designer at the engineering company Punch Through Design, where she worked on projects with Arduino microcontrollers. After she quit her internship, her US visa lapsed, and she returned to Sweden to live with her mother. She also held brief jobs in technology journalism.

Giertz created her YouTube channel in March 2013. Her first robot video was of a toothbrush helmet, posted on YouTube on August 2015. She had made the robot for a children's show pilot on electronics, but she posted it online after the show was not picked up. This seven-second video showed the helmet moving across her face without using toothpaste. She posted twelve more videos in 2015, featuring other robots inspired by everyday tasks, including one that electrically shocked her face while she read comments on her videos.

Giertz's videos became popular on a subreddit called "Shitty Robots", with one post becoming the subreddit's most popular of all time. She gained the nickname "Queen of Shitty Robots", which she began using herself. Most of Giertz's early videos received hundreds of thousands of views, including one that received 500,000 views within a day of being posted on Reddit. She also received tens of thousands of subscribers on Instagram.

A video titled "The Breakfast Machine", posted in November 2015, was Giertz's first to feature a robotic arm. In the video, it poorly pours milk and cereal, then holds up an empty spoon. On November 11, she posted "The Wake-up Machine", an alarm clock that slaps the user using a rubber hand that had originally been a Halloween decoration; the video showed it tangling Giertz's hair. She said this creation was "the first one that really took off". "The Breakfast Machine" and "The Wake-up Machine" each received one million views. In December 2015, she posted the "Chopping Machine", which used two knives to slice vegetables, in a video that parodied infomercials. Other creations included a drone that cut the user's hair (tested on a mannequin), a robot that used tongs and rubber hands to generate applause, one that shampoos the user's hair, and one that lifts up soup using 3D-printed parts. Content creation became Giertz's full-time job by March 2016, at which point her YouTube channel had over 100,000 subscribers.