So many to choose from since a lot of artists thrive on controversy.
Here are some that come to mind that would be fun for a paper:
POOP VIRGIN MARY WITH PORNO COLLAGE:
Chris Ofili won the Tate's prestigious Turner Prize in 1998. He is famous for the Holy Virgin Mary, canvas with elephant dung, exhibited at the Brooklyn Museum in 1999.
Ofili’s depiction of the Virgin Mary, was at issue in a lawsuit between the mayor of New York City, Rudy Giuliani, and the Brooklyn Museum of Art when it was exhibited there in 1999 as a part of the "Sensation" exhibit. The painting depicted a black African Mary surrounded by images from blaxploitation movies and close-ups of female genitalia cut from pornographic magazines, and elephant dung. These were formed into shapes reminiscent of the cherubim and seraphim commonly depicted in images of the Immaculate conception and the Assumption of Mary. Following the scandal surrounding this painting, Bernard Goldberg ranked Ofili #86 in 100 People Who Are Screwing Up America.
PISS CHRIST:
Although not a painting it is hard to beat Andres Serrano’s “Piss Christ” for controversy. Piss Christ is a 1987 photograph by photographer Andres Serrano. It depicts a small plastic crucifix submerged in a glass of the artist's urine. The work was vandalized at the National Gallery of Victoria, Australia, and gallery officials reported receiving death threats in response to Piss Christ. Supporters argued that the controversy over Piss Christ is an issue of artistic freedom and freedom of speech. The piece was a winner of the Southeastern Center for Contemporary Art's "Awards in the Visual Arts" competition, which is sponsored in part by the National Endowment for the Arts, a United States Government agency that offers support and funding for artistic projects.
ALL BLACK-ALL WHITE PAINTINGS
How about Alexander Rodchenko’s all black painting in response to Kasimir Malevich’s all white paintings? That was controversial.
LIVING PAINT BRUSHES
How about Yves Kline painting nude models who rolled around on the canvas as living paint brushes?
FROM PIETA TO PEDOPHILE:
This painting of the Virgin Mary cradling the Dead Christ in “Pieta of Villeneuve-lès-Avignon”:
ALSO WORTHY
Also worthy of note for raising people’s awareness and stirring the dander of the establishment at their time period:
Manet's "Luncheon on the Grass" (Clothed men picnicking with naked women)
Manet's “Olympia” (nuSevilletitute)
Jacques-Louis David's "The Death of Marat";
Goya's "Executions of the Third of May, 1808";
Turner's "Slave Ship" and “The burning of The Houses of Parliament”.
Picasso's "Guernica";
Gericault's, "Raft of the Medusa".
GROSS NUDES
URBAN GRAFFITI:
For more on-going controversy don’t forget Contemporary urban gorilla graffiti artist Banksey.
EXPENSIVE CHINESE POLITICAL CONTROVERSY PAINTINGS:
Yue Min Jun’s controversial painting "EXECUTION" is the most expensive Chinese contemporary art sold to date at 2.9 million pounds ($5.9 million) in a London Auction!
or his “The Pope and MasChie at Chio” would be interesting paintings to study.