Nicolas Nilo César de Oliveira (born August 4, 1987) is a Brazilian freestyle swimmer who specializes in sprint events.
Oliveira swam at the 2006 Pan Pacific Swimming Championships, where he finished 6th in the 4 × 200-metre freestyle, 14th in the 100-metre freestyle, 25th in the 200-metre freestyle, and was disqualified at the 4 × 100-metre freestyle.
His first appearance in World Championships, was at the 2007 World Aquatics Championships held in Melbourne, where he helped the 4 × 100-metre and 4 × 200-metre freestyle relay to qualify for the 2008 Summer Olympics. Nilo earned 46th place in the 50-metre freestyle, 26th in the 100-metre freestyle, 17th in 200-metre freestyle, 8th in the 4 × 100-metre freestyle, and 11th in the 4 × 200-metre freestyle.
At the 2007 Pan American Games, Nilo won the gold medal in the 4 × 100-metre freestyle relay and in the 4 × 200-metre freestyle. He also ranked fourth in the 200-metre freestyle.
At the 2008 Summer Olympics in Beijing, he participated in the 4 × 100-metre freestyle relay (where he was disqualified), 4 × 200-metre freestyle (16th place), and 4 × 100-metre medley (14th place).
At the 2009 World Aquatics Championships in Rome, along with César Cielo, Guilherme Roth, and Fernando Silva, he finished 4th in the 4 × 100-metre freestyle relay; with Thiago Pereira, Rodrigo Castro, and Lucas Salatta, he got the 10th place in the 4 × 200-metre freestyle. He was also in the 100-metre freestyle finals, placing 8th, and finished in 18th place in the 200-metre freestyle.