Jacobje Jantje "Cobie" Buter (also Coby; born 17 May 1946) is a retired Dutch swimmer who won the bronze medal in 100 m backstroke at the 1970 European Aquatics Championships. She also competed at the 1968 Summer Olympics and finished seventh in the 4 × 100 m medley relay. She helped the Dutch team to set a new European record in the same event in 1968. Between 1965 and 1970 she won four national titles and set four records in the 100 m backstroke.