Philipp Peter Roos (later surnamed Rosa di Tivoli; 1651-1706), was a German Baroque painter.
He was born in Frankfurt am Main and learned to paint from his father, the landscape painter Johann Heinrich Roos.He was the brother of the painter Johann Melchior Roos, who briefly worked with him in Italy. As a young man, he painted in the style of his father. He was called to paint for Charles I, Landgrave of Hesse-Kassel, who liked him so much, he gave him a sum of money to travel to Rome with,which he did in 1677. He became a member of the Bentvueghels with the nickname "Mercury" and earned money making small paintings and sketches for tourists.
He fell in love with the daughter of Giacinto Brandi, whom he later married. They lived in a large house in Tivoli, near Rome, whence his surname. In Tivoli, they kept a menagerie of various animals so Roos could draw from live poses. This house was called the "Noah's Ark" by their friends. In his Italian style, he painted life-size figures and animals in a broad manner and a heavy brown tone.