Merrill Cook (born May 6, 1946) was a Republican member of the United States House of Representatives from Utah.

Cook, a member of The Church of Jesus Christ of Latter-day Saints was born and raised in Salt Lake City, Utah. He graduated from East High School in 1964 and the University of Utah in 1969 and earned an M.B.A. from Harvard Business School in 1971. Upon receiving his degree, Cook was hired as a budget analyst by Arthur D. Little, Inc. He left the corporation in 1973 to co-found Cook Slurry Company, a mining explosives manufacturer. Merrill Cook's father was the noted scientist Melvin A. Cook who, among his many accomplishments, pioneered the development of slurry explosives.

Cook made his first run for office in 1984, when he lost a bid for the Utah Board of Education. In 1985, he ran for mayor of Salt Lake City and lost to Palmer DePaulis. He made an unsuccessful bid for the Salt Lake County commission in 1986.

Cook had been a lifelong Republican, but in 1986, he broke ranks and formed the Utah Independent Party. He ran as that party's gubernatorial candidate in 1988 and got 22% of the vote, siphoning off enough votes from Democrat Ted Wilson to hand incumbent Republican Norm Bangerter another term. In 1992, he ran again and came in second to Mike Leavitt with 34%, with Democrat Stewart Hanson coming in at 23%. He was also that party's nominee for the 2nd District in 1994, coming in third with 18%.

However, in 1996, after incumbent Republican Enid Greene announced she wouldn't run for reelection due to a scandal, Cook rejoined the Republican Party. He managed to come in second at the state convention behind the choice of the party establishment, Salt Lake City accountant R. Todd Neilson, getting just enough votes to deny Neilson the nomination outright. Cook won the primary a few months later by 4 percentage points. He faced future Salt Lake City mayor Rocky Anderson in the general election. Calling Anderson "too socially liberal for Utah," Cook won with 56 percent of the vote despite losing the district's share of Salt Lake City.

In 1998, Cook was accused of instances of erratic behavior. He was briefly banned from state Republican headquarters after an obscenity-laced tirade, his reaction to being told his name had been eliminated from a GOP get-out-the-vote effort to which Cook's campaign had contributed $25,000. He, nevertheless, won by 10 percentage points. He demoted his chief of staff Janet Jenson a few days after the election; in an email, Jenson told her colleagues, "Merrill has taken up permanent residence in whacko land. If he asks you to fax his underwear to the speaker's office, please just do it."

In 2000, the Democrats nominated environmental consultant Jim Matheson, the son of former popular Democratic governor Scott Matheson. Polls showing Cook far behind Matheson made many Republicans nervous about their chances of holding the seat, even though the national party strongly backed Cook. However, in an ominous sign, Cook was forced into a primary against computer tycoon Derek Smith, who was making his first run for elected office. In the primary, Smith defeated Cook by a 15-point margin, taking 57 percent to Cook's 42 percent. Matheson routed Smith at the general election in November.

Cook ran for mayor of Salt Lake County in 2004 as an independent, but garnered only 8 percent of the vote in a race won by Democrat Peter Corroon. In 2006 he tried to challenge 3rd District Congressman Chris Cannon but was eliminated on the first ballot.

He is now running for his old seat in the 2nd district in the 2008 election.

Cook's political activities have largely been enabled by self financing. His personal expenditures for campaigns for office and ballot initiatives have been over $4 million