He also acted extensively in numerous television series such as The Practice, Studio 60 on the Sunset Strip, The Good Wife, Cobra Kai, Briarpatch, Working Class, and Dead to Me.

He had been working in a steel mill,[10] but he quickly switched to drama, debuting as the martyred Thomas Becket in a campus production of T. S. Eliot's Murder in the Cathedral.

[14] In New York City, Off-Broadway roles included Jonathan Jeremiah Peachum in the revival of Threepenny Opera and in Otway's Venice Preserv'd in late 1955.

[15] Asner scored his first Broadway role in Face of a Hero alongside Jack Lemmon in 1960, and began to make inroads as a television actor, having made his TV debut in 1957 on Studio One.

[17] Other television series starring Asner in regular roles include Thunder Alley, The Bronx Zoo, and Studio 60 on the Sunset Strip.

[22][23][24] He also provided the voices for Joshua on Joshua and the Battle of Jericho (1986) for Hanna-Barbera, J. Jonah Jameson on the 1990s animated television series Spider-Man (1994–98); Hoggish Greedly on Captain Planet and the Planeteers (1990–95); Hudson on Gargoyles (1994–96); Jabba the Hutt on the radio version of Star Wars; Master Vrook from Star Wars: Knights of the Old Republic and its sequel; Roland Daggett on Batman: The Animated Series (1992–94); Cosgrove on Freakazoid!

He was even nominated for a Daytime Emmy Award for Outstanding Performer in an Animated Program but lost to Eartha Kitt for Nick Jr.'s Wonder Pets!.

"[28] He appeared in the mid- to late-2000s decade in a recurring segment on The Tonight Show with Jay Leno, entitled "Does This Impress Ed Asner?

He made an appearance in the independent comedy feature Not Another B Movie, and had a role as billionaire Warren Buffett in HBO's economic drama Too Big to Fail (2011).

[39] He also recorded for a public radio show and podcast, Playing On Air, appearing in Warren Leight's The Final Interrogation of Ceaucescu's Dog with Jesse Eisenberg, and Mike Reiss's New York Story.

[40][41] Asner was the voice-over narrator for the 2016 documentary Behind the Fear: The Hidden Story of HIV, directed by Nicole Zwiren, a controversial study on the AIDS debate.

[43] During interviews for a 2019 book on the history of Chicago theater, Asner told the author he preferred to be credited for his work as "Edward" rather than "Ed" because he felt the longer name held the page or screen better.

Asner also had a recurring guest role in the 2018–present series Cobra Kai, portraying Johnny Lawrence's step-father, Sid Weinberg, in seasons one and three.

[49] Beginning in 2016, Asner took on the role of Holocaust survivor Milton Salesman in Jeff Cohen's acclaimed play The Soap Myth in a reading at Lincoln Center's Bruno Walter Theatre in New York City.

[10] Asner had completed several roles in a number of TV series and films at the time of his death in August 2021, including three of his final productions released posthumously on the Disney+ streaming service.

Asner's cameo appearance as the Ghost of Claude in the Halloween special Muppets Haunted Mansion (2021) was posthumous, and he provided the voice of Grandpa Heffley in the Disney+ animated film adaptation Diary of a Wimpy Kid: Rodrick Rules (2022), released over a year after his death.

[55] In 2011, Asner endorsed Democratic candidate Marcy Winograd who finished 4th in the 16-candidate primary behind eventual winner Janice Hahn, in California's 36th congressional district special election.

[61] In April 2004, Asner wrote an open letter to "peace and justice leaders" encouraging them to demand "full 9–11 truth" through the organization 9-11 Visibility Project.

[62] In 2011, Asner hosted the Architects & Engineers for 9/11 Truth documentary on the collapse of 7 World Trade Center, which endorses the theory that the building was taken down by controlled demolition.

Asner also sat on the advisory board for Exceptional Minds, a non-profit school and a computer animation studio for young adults on the autism spectrum.

[67] Asner was a supporter of Humane Borders, an organization based in Tucson, Arizona, which maintains water stations in the Sonoran Desert for use by undocumented migrants, with the goal of preventing deaths by dehydration and exposure.

The Center provides arts and vocational enrichments, counseling services, and support groups and camps to special needs individuals and their families.

[69] Asner served two terms as president of the Screen Actors Guild, in which capacity during the 1980s he opposed United States policy in Central America, working closely with the Alliance for Survival.

On March 30, 2012, the Screen Actors Guild (SAG) and the American Federation of Television and Radio Artists (AFTRA) completed a merger of equals, forming a new union SAG-AFTRA.

[76] He also served as a board member and adviser for Aspiritech, a nonprofit organization that trains high-functioning autistic persons to test software and perform quality-assurance services for companies.

[83] Numerous celebrities paid tribute to Asner, including Maureen McCormick, George Takei, Mark Hamill, Michael McKean, Bradley Whitford, Josh Gad, Mia Farrow, Andy Richter, Katie Couric, Denis O'Hare, Mira Sorvino, Eric Stonestreet, Niecy Nash, Yvette Nicole Brown, Michael Moore, Rosario Dawson, Rosanna Arquette,[84] Ben Stiller, The Muppets, William Baldwin,[85] Greg Weisman,[86] William Zabka, Ralph Macchio, Bob Peterson, Bill Farmer, and Zooey Deschanel.