Marcus Ulf Johan "Bosse" Grönholm (born February 5, 1968) is a Finnish former rally and rallycross driver, being part of a family of the Swedish-speaking population of Finland lineage.

A staggering string of fastest stage times one year as a privateer, on the final day of the Rally Finland, subsequently brought him to the attention of such factory teams as Ford, Toyota and Peugeot, who all presented him with offers for further employment.

Consequent wins, including on his home round of the series, were sufficient to see off closest points challenger, Subaru's Richard Burns and land a shock first title after finishing second to the Englishman in the Rally of Great Britain.

Fourth in France and sixth in Spain after a wrong tire choice was followed by another crash in Great Britain when he hit a pile of logs on a stage.

Grönholm took an immediate dislike to the new car because of its poor reliability, battling gearbox problems in Monte Carlo and power steering issues in Sweden.

After a difficult start with crashes in Monaco and Sweden Grönholm finished second in Mexico and New Zealand and was in contention for the win in Italy until a hefty roll down a hill cost him a heap of time and he had to settle for third.

Retirement in Cyprus was followed by another third in Turkey where he lost a fight with Solberg for second; however both were comfortably beaten by Loeb who dominated the year with ten wins and Michelin tires that were superior to the Pirelli on the Peugeot.

On his debut, in January, he won his first ever tarmac rally in Monte Carlo, beating Sébastien Loeb by over a minute, albeit beaten by the Frenchman on the road with the championship's unliked 'Superally' regulations coming to his rescue as a shunt for the Citroën hastened its exit from Leg One.

Loeb's hopes seemed to be coming to fruition when yet another victory in Cyprus brought him to the brink of the title; however he was to suffer his own blow days later when injury from a biking accident forced him out of the last four rounds of the series.

Grönholm was able to push within one point of the lead in the total standings as Loeb recovered, but his claim to the title was finally extinguished when he rolled out of contention on the first leg of the penultimate event in Australia.

Some solace for Grönholm, though, came in that another victory in New Zealand ahead of teammate Mikko Hirvonen was to confirm the manufacturers' title for his Ford team over Loeb-less Kronos Citroën.

He claimed third place in the 75ème Rallye Automobile de Monte-Carlo behind the dominant returning works Citroens, and then the top spot in the Swedish Rally, mirroring the previous year's result.

On April 16, 2008, Grönholm, at a press conference in the Kungsträdgården of Stockholm, announced a limited programme to take part in at least five rounds of the FIA European Championships for Rallycross Drivers (ERC).

[7] In 2011 Grönholm participated in the American Global RallyCross Championship (GRC) in a 560 bhp Best Buy Ford Fiesta Mk7 prepared by the Swedish company Olsbergs MSE.

He stated that he was not aiming for the win and that "it will be fun to return [to the WRC], even in an ad hoc way, in a car that I don't know at all and after a year where I competed in some rallycross events.

"[10] Despite this Grönholm performed well and stayed in touch with the leaders; he was in 4th position when he crashed on Saturday's opening stage, damaging the car's engine and ending his rally.

[11] Grönholm took part in the 2010 Rally Sweden driving a Ford Focus RS WRC 08 for Team Therminator, alongside countryman Matthias Therman.

[12] Grönholm made a return to the wheel of a Prodrive-run rally car in September 2010 when he test drove the Mini Countryman WRC in Portugal.