YouTube
Fischbach registered his first YouTube channel on March 6, 2012. He originally intended to upload comedy sketches and action videos. He named the channel "Markiplier", a portmanteau of Mark and multiplier, as he would be portraying all the characters in the sketches. Fischbach later said it was a "really dumb name". However, Fischbach also had a lifelong interest in video games and decided to make gaming videos while the trend was growing. His first series was a Let's Play of Amnesia: The Dark Descent (2010), and the channel reached over 94,000 subscribers within the year.
YouTubers with over one thousand subscribers were then eligible to earn money under YouTube's AdSense program. However, Fischbach had problems with his AdSense account which prevented him from monetizing his videos, and he was forced to move to his current channel in April, originally named "markiplierGAME", now named "Markiplier". He dropped out of college the same year to support his growing online career, only two semesters away from graduating. In early 2014, Fischbach moved to Los Angeles to be closer to potential business opportunities.
Fischbach and Janet Varney co-hosted the 2015 South by Southwest Gaming Awards, and he was featured in YouTube Rewind. He was ranked sixth in a list of the twenty most influential celebrities among teenagers in the United States. Fischbach and fellow YouTuber Jenna Mae appeared on Jimmy Kimmel Live! in September 2015 following backlash Kimmel received regarding jokes he made about YouTube and Let's Play videos.
Fischbach began living with fellow YouTubers Daniel Kyre and Ryan Magee, who ran the YouTube channel Cyndago. In September 2015, Kyre was found in critical condition after attempting suicide in his room. He was hospitalized but was taken off life support two days later. Cyndago was disbanded, and Fischbach went on hiatus from YouTube for a month before returning on October 5. He reached ten million subscribers on the 14th.
In November 2016, Fischbach signed with talent agency William Morris Endeavor (WME). His first project with WME was his "You're Welcome Tour" in Spring 2017, in which Fischbach and four other YouTubers—Muyskerm, Barnes, Tyler Schied, and Ethan Nestor—performed 31 shows across the United States and Europe. Fischbach had said to Variety that he was interested in more traditional entertainment. Taking five months to plan, he incorporated musical, comedy, and improv elements and audience participation in the tour. In January 2018, Fischbach began producing exclusive content for Twitch as part of a deal with Disney Digital Network.
His YouTube channel reached 20 million subscribers in March, before going on another hiatus in June to mourn his step-niece Miranda Cracraft, who had been killed in a car accident at the age of nineteen, raising over $79,000 for her funeral through GoFundMe.
In October 2019, an interactive special, A Heist with Markiplier, was released as his first YouTube Original. Produced by Fischbach and Rooster Teeth, the special follows two burglars—the viewer and Fischbach—and contains 31 possible endings. Fischbach had released a similar project titled A Date with Markiplier in 2017.
On November 15, 2019, Fischbach launched a new channel with fellow YouTuber Ethan Nestor (formerly known online as CrankGameplays) called Unus Annus (Latin for "one year"), a channel which planned to upload a video every day for one year, after which the channel would be deleted along with its videos. The channel rose to early success, gaining 1 million subscribers in its first five days and 4.56 million in its last few minutes, and over 11.5 million video views in its first week. Following a final 12-hour live stream that peaked at over 1.5 million concurrent viewers, the channel was deleted by Fischbach and Nestor on November 14, 2020, at 12:00 a.m. PST.
