An influential art historian, curator, and author, Bruce Guenther has contributed to the cultural life of Oregon and the Northwest for more than five decades. During his fourteen-year tenure as curator at the Portland Art Museum (PAM), he actively promoted local and regional artists, exposed Oregon audiences to national and international contemporary art, and expanded the museum’s permanent collection with more than four thousand examples of modern art. His many publications, recorded lectures, and exhibitions have contributed to his legacy as an impassioned advocate for art.

Bruce Guenther was born in Medford, Oregon, on March 4, 1948. After graduating from Medford Senior High School (1966), he attended Southern Oregon University (then Southern Oregon College) where he was inspired by his professors Betty LaDuke in art and Lawson Inada and Charles Ryberg in English Literature. Before earning a bachelor of science in Applied Design in 1971, Guenther spent a year with Volunteers in Service to America organizing migrant communities in Colorado. He also taught in the Head Start Program in Colorado and Oregon. In 1973, his one-year curatorial internship at PAM launched what would become his distinguished career as a museum professional.

From 1974 to 1979 at Washington State University's Museum of Art in Pullman, Guenther honed his skills as its first curator and, later, as its director. He organized survey exhibitions of drawings, sculpture, photography, and fiber art, as well as symposia of nationally known artists and art historians such as Robert Motherwell and Albert Elsen. In subsequent curatorial positions at the Seattle Art Museum (1978-1987), Museum of Contemporary Art Chicago (1987-1991), and Newport Harbor Art Museum (later the Orange County Museum of Art) in California (1991-1999), Guenther conceived dynamic exhibition programs of general surveys of modern art and single-artist shows. He cultivated collectors and benefactors and organized trips to major art centers with museum members and trustees to broaden their experience of contemporary art.

Guenther returned to Oregon in 2000 as Curator of Modern and Contemporary Art at the Portland Art Museum, assuming the additional role of chief curator the following year. He expanded the publications program and organized exhibitions, beginning with "Clement Greenberg: A Critic's Collection" with an accompanying catalogue (2001) that documented the museum's acquisition of 159 works from Greenberg, one of the twentieth century's most famous American art critics.

In 2010, Guenther curated Disquieted, a landmark exhibition that captured artists' concerns with feminist politics, sexual orientation, and racial difference—subjects he had examined before with States of War (Seattle Art Museum, 1985) and The Essential Gesture (Newport Harbor Art Museum, 1994). Disquieted featured painting, sculpture, photography, and video by an international roster of artists, including Sanford Biggers, Tracey Emin, Andreas Gursky, Glenn Ligon, Takashi Murakami, Wangechi Mutu, Shirin Neshat, and John Sonsini. Oregonian critic D. K. Row described Disquieted as its curator's "emotional pulse-reading of these times of anxiety, duress, [and] technological advancement."

With a program of solo shows dedicated to artists such as Sophie Calle, Pierre Huyghe, Bruce Nauman, Roxy Paine, Kiki Smith, and Kehinde Wiley, Guenther offered PAM audiences a wide window onto the contemporary scene. Guenther's momentous Mark Rothko retrospective in 2012 was the first to present early experimental work from Oregon and New York alongside what Portland Monthly critic Randy Gragg identified as "the strange radiance" of Rothko's mature paintings. Guenther also instituted a series of collaborative events and new commissioned works connecting artists exhibiting at PAM with the Portland Opera, Oregon Ballet Theatre, Third Angle Music, and Friends of Chamber Music. Undeterred by the challenges of presenting large-scale sculpture, he rolled out exhibitions devoted to Gaston Lachaise and Ursula von Rydingsvard, as well as retrospectives of Oregonians Lee Kelly and Hilda Morris.

The monumental, 30-foot-tall painted-aluminum Brushstrokes (1996) by Roy Lichtenstein installed in front of PAM remains one of Guenther's most significant acquisitions. His relationships with philanthropists and his fundraising initiatives allowed him to obtain for the museum signature works by Anthony Caro, Marcel Duchamp, Ed and Nancy Kienholz, Larry Poons, and Robert Rauschenberg, as well as Vincent van Gogh's Ox Cart (1884). In 2011, Man Ray's surrealist Gift (1921/1972), a hand iron bristling with tacks, entered PAM's collection—donated by Guenther himself and Dr. Eduardo Vides, his life partner since 1995.

The opening at PAM of the Arlene and Harold Schnitzer Center for Northwest Art in 2000 spurred Guenther to secure the first-ever endowment for a curatorial position at the museum, the Arlene and Harold Schnitzer Curator of Northwest Art (2006). Guenther pursued additional multimillion-dollar curatorial endowments, including the Arlene and Harold Schnitzer Curator of Asian Art (2008), Minor White Curator of Photography (2011), Richard and Janet Geary Curator of European Art (2012), and Robert and Mercedes Eichholz Curator of Modern and Contemporary Art (2012). Guenther held the endowed Eichholz position for two years until his retirement in 2014.

Guenther became Adjunct Curator for Special Exhibitions at the Oregon Jewish Museum and Center for Holocaust Education beginning in 2016, and presented work by Jewish artists such as Grisha Bruskin, Judy Chicago, Helen Frankenthaler, and R. B. Kitaj. Before he left that position in 2023, he curated The Jews of Amsterdam, an exhibition of Rembrandt etchings juxtaposed with views of the Amsterdam Jewish quarter by Dutch-born Oregon painter Henk Pander.

For his institution-building endeavors and unfailing support of Oregon artists, Guenther received the Portland Art Dealers Association Award for Service to the Visual Arts in 2015, an Honorary Doctor of Arts from the Oregon College of Art and Craft in 2016, and the Distinguished Alumni Award from Southern Oregon University in 2019.