A native of Long Island, New York, Guggenheim practiced law at one of Boston’s most prestigious firms before getting hired on the writing staff of David E. Kelley’s Emmy-winning show about Boston attorneys, The Practice. Guggenheim then joined Law & Order, where he wrote for three seasons before moving on to the critically acclaimed series Jack & Bobby and the ratings juggernaut CSI: Miami.

It was Jack & Bobby that introduced Guggenheim to Greg Berlanti, and the two resolved to create a show together, a pact which led to the development of Eli Stone, which garnered them a Writers Guild Award nomination for Best Drama Teleplay.

Guggenheim has continued to collaborate with Berlanti on the feature film versions of the DC Comics characters Green Lantern and The Flash. Green Lantern was released as a major motion picture starring Ryan Reynolds in June 2011. The duo then went on to co-create Arrow, which spawned a “universe” of related series and events, culminating in 2020’s Crisis On Infinite Earths, a five-hour, six-series crossover.

2014 marked Guggenheim’s entry into the world of prose, publishing his first novel Overwatch (Mulholland Books/Little, Brown), which Publishers Weekly called “a high energy debut…[which] will appeal to readers who appreciate an underdog.” His next book, In Any Lifetime, is coming from Lake Union Publishing on August 1st.

In 2020, directed his first episode of television (DC’s Legends of Tomorrow) which made several “best of year” lists.

For nearly 10 years, he collaborated with Guillermo del Toro on the Emmy Award-winning and BAFTA-nominated Tales of Arcadia trilogy for Netflix, which culminated with the Trollhunters: Rise of the Titans movie in 2021. His feature film work also includes writing screenplays for Robert Downey Jr. and Jake Gyllenhaal.

A life-long comic book fan, Guggenheim has been writing comics professionally for twenty years, working on titles for both Marvel Comics (Blade, X-Men, Spider-Man), DC Comics (The Flash, Superman, Batman), and original creator-owned works (Resurrection, Halcyon, Nowhere Man, Jonas Quantum, Stringers). He is currently developing two of his creator-owned graphic novels Too Dead to Die and Last Flight Out as a movie for Universal Studios and a television series for Netflix, respectively.

Guggenheim is married to fellow writer/showrunner Tara Butters (Reaper, Agent Carter, Gen V). They have two daughters, two cats, and two dogs.

Keep up to date on his latest projects with LegalDispatch, a weekly newsletter where he shares news and notes about writing, comics, and the entertainment industry. Check it out at on Substack.

Subscribe to Marc's Newsletter, LegalDispatch