Jeff Koons has a knack for combining art and commerce. The American artist is taken seriously as a contemporary artist, and his works fetch top prices at international art auctions. The artist, renowned for its crowd-pleasing exhibitions, was the subject of a retrospective at the Guggenheim Museum in the Spanish city of Bilbao in 2015.

The oversize sculpture of a dog stood guard in front of the Guggenheim Museum in Bilbao once before, in the 1990s. The 12 meter-high "Puppy" is carpeted with flowering plants - and, back then, was a huge hit with tourists. Jeff Koons created the imposing figure as a surprise coup for the 1992 Documenta exhibition - to which he had not been invited.

Over time, Koons' works grew in proportion and became ever more spectacular. Prices skyrocketed too. Collectors include Ukrainian oligarch Victor Pinchuk and French billionaire entrepreneur Francois Pinault, who holds a majority share in Christie's auction house. Koons' "Balloon Dog" sold at a 2013 auction there for a record $58.4 million.

Critics argue whether everything Jeff Koons' production lines create should be taken seriously as art. "Ushering in Banality" is what the artist once wryly called one his works. Koons says he always wants to reach a mass audience. He certainly is successful at that: in China, his trendy sculptures are among the most-copied works of art.

In his early years at the Baltimore Institute of Art and the Chicago Art Academy, Koons was a diligent student of art history. His artworks are richly embellished with quotes from famous works from antiquity to modern times. He also likes to copy photos and use that in his sculptures - and has been sued more than once for copyright infringement.

Born on January 1, 1955, Koons sold his first painting at age 11. His father was an interior designer and owned a furniture store. As a young boy Koons became intimately acquainted with plastic decoration and backdrops there. As he told one interviewer, his later motifs are often rooted in his childhood. After completing art studies, he worked at the Museum of Modern Art (MoMa) in New York.

Everything Koons publishes as art is factory-made - in cool, impersonal perfection. He employs 128 people in his studio, which looks like a factory hall. 64 people work in the painting department and 44 make sculptures, all according to his specifications. His name is the brand and sometimes more important than the products he brings to the market - including these basketballs floating in water.

For his 1990 series "Made in Heaven," Koons used the Hungarian-Italian porn star Cicciolina (Ilona Staller) as a model and had a passionate affair with her. Their marriage made worldwide headlines in 1991. Pornographic scenes, plump silicone breasts and kitschy imagery were now part of Koons' standard repertoire.

Jeff Koons trained his sales ability early on and, as an artist, has employed it with great success. "It is, above all, about communication. And art is communication" - a credo with which he mercilessly exploits the popularity of the people he portrays in his works, including Michael Jackson. Koons also designed the album cover for Lady Gaga's 2013 album "Artpop."

Koons has regularly drawn criticism for the perceived banality of his subjects, which act like set pieces from advertisements. But museum visitors admire the radiance of works such as his "Hanging Heart," displayed in the 2008 Berlin exhibition "The Cult of the Artist."

The day after the November 2015 Paris attacks, which left over 130 people dead, the city was in mourning. When German pianist Davide Martello began playing John Lennon's "Imagine" outside the Bataclan on a piano he had transported from Germany, a crowd quickly gathered. Martello later told The Guardian that "I wanted to be there to try and comfort, and offer a sign of hope."

After the chaos of a tragedy, a simple visual image can be a comfort. French graphic artist Jean Jullien posted a hand-painted peace sign incorporating an image of the Eiffel Tower on social media after the November 2015 attack in Paris. It quickly became an iconic symbol of sympathy with survivors.

Artists do not always play a peaceful role. The comic artist known as Charb was famous for publishing offensive caricatures of religions, including Islam. After Islamist gunmen shot him and his colleages to death in the offices of Charlie Hebdo on Jan. 7, 2015, demonstrators used his images to defy the attackers and their supporters.

Artists are sometimes the targets of terrorist groups. Such was the fate of Syrian pianist Aeham Ahmad, who studied music in Damascus and Homs but spent much of his life in a refugee settlement. It was on a bombed-out street there that Ahmad gained international attention, playing piano in a YouTube video. After ISIS militants burned his instrument, he fled to Germany and now lives there.

Aristotle's theory of catharsis - purging emotions through theater - lives on. Austrian Elfriede Jelinek crafted her play "Anger" (pictured above in a 2016 production at the Hamburger Thalia-Theater) while in shock from the 2015 attacks in Paris. The title points not only to the anger of the attackers, but also the hatefulness of some responses, as well as the agony of those caught in the middle.

On March 13, 2016, Al-Qaeda militants gunned down 19 people on the Ivory Coast's sandy Grand Bassam beach. Ten days later, a number of the country's pop stars released a music video to reclaim the space. "Meme pas peur" is the name of the song - "Not even scared" - and the defiant words ring true among performers as they dance on the sun-bleached sand, no blood in sight.

Not all artistic responses to violence are literal. The vivid colors and lively shapes of Guillaume Bottazzi's abstract art speak for themselves as a reponse to tragedy. Since the end of October, he has been working on a mural in Brussels's Place Jourdan as a permanent memorial to the victims of the March 22 attacks in the city.

American pop artist Jeff Koons unveiled his plan for "Bouquet of Tulips 2016" at a ceremony in Paris in November. The forthcoming sculpture, by one of the world's wealthiest artists who hires workers to construct his designs, was donated in honor of the victims of the multiple Paris terrorist attacks of 2015.

On December 20, a day after an attack on a Berlin Christmas market claimed 12 lives, the Brandenburg Gate was lit with the colors of the German flag. On Friday, December 23, the city will hold a six-hour long memorial concert featuring several German musicians as a sign of Berlin's resilience to the disruption of an otherwise festive public life in the week before Christmas.