Guillermo Timoner Obrador (born 24 March 1926) is a retired Spanish cyclist. With six gold and two silver medals won in the UCI Motor-paced World Championships between 1955 and 1965 he is one of the most successful motor-paced racers of all times. During his career, which spanned 52 years, he also won 29 national titles in various cycling disciplines.

Before becoming professional cyclist he worked as a carpenter. He won his first competition in 1943 and retired around 1965 to work in commerce. He reappeared as a cyclist in 1983, and in 1984 took part in the World Championships in Barcelona in the masters category. In 1995, aged 69, he won the European Championships, biking a distance of 53.4 km with an average speed of 37.4 km/h.

In 1998 he received the Ramon Llull Award from the government of the Balearic Islands.

He lives in his native Felanitx, Balearic Islands, Spain. His younger brother Antonio is also a former competitive cyclist.