Bob may mean:

 A shortening of the name Robert
 Bob (physics), the weight at the end of a pendulum
 "Bob" (song), a song by "Weird Al" Yankovic from Poodle Hat
 "Bob" (Red Hot Chili Peppers Song), a song by the Red Hot Chili Peppers from the album One Hot Minute
 J.R. "Bob" Dobbs, a figurehead of the satirical Church of the SubGenius
 Bob cut, a hairstyle
 Bob FM, a radio format in Canada and the U.S.
 Hurricane Bob, a 1991 hurricane
 Microsoft Bob, an unsuccessful software product
 A shilling
 Bob, a television comedy starring Bob Newhart
 Bob of Alice and Bob, placeholder characters in cryptography and physics problems

In acronyms:
 "B.O.B. (Bombs Over Baghdad)", a 2000 single by OutKast
 Bank of Baroda, in India
 Band of Brothers, an acclaimed television miniseries
 Battle of Britain
 Battle of the Bands, a competition between multiple bands
 Bayerische Oberlandbahn, a private German railway
 Beast of Burden
 Bend over boyfriend
 Berlin Operating Base, the CIA station in Berlin during the Cold War
 Berner Oberland Bahn, a mountain railway in Switzerland
 Best of Breed, an award in dog shows and other settings
 Blitter object, a graphics construct
 Bob-omb, a character in the Nintendo Mario video games
 Breakout box, an electronics component
 Bug-out bag, an emergency kit
 Bora Bora Airport's IATA airport code
 4-bromo-2,5,beta-trimethoxy-phenethylamine, a             drug 
 the ISO 4217 code for the Bolivian boliviano (currency) 
 Bank One Ballpark, or Chase Field
 Basketball Owl Band at Rice University
 Body Opponent Bag, a punching bag shaped like a human head and torso
 BOB (Born on Board), the humans in the Marathon Trilogy 

In fictional characters:
 Bob (Twin Peaks), a villain on the television show Twin Peaks
 Bob (Blackadder character), the name of two characters in the television comedy Blackadder
 Bob (The Dresden Files), a character featured in the novels and TV show The Dresden Files
 Bob (First Comics), a "watchlizard" from the First Comics series GrimJack
 Bob the Builder
 Bob the Killer Goldfish, a character in the Earthworm Jim universe.
 Silent Bob, a character in Kevin Smith's View Askewniverse
 Almighty Bob, a fictional deity in Mostly Harmless by Doulgas Adams
 Bob, one of the human characters on Sesame Street
 Bob, one of the main characters in ReBoot
 Bob, the Jagex cat in RuneScape
 Evil Bob, a random event in RuneScape
 Bob, a character in Bubble Bobble
 Bob, a character in Weebl and Bob
 Bob, a principal character in What About Bob?
 Bob, one of the two eponymous main characters of the sprite comic Bob and George
 Smilin' Bob, a character in commercials for Enzyte
 Bob Vorsh, a villain in the webcomic Jack (webcomic)
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Famous people with the given name Bob

 Bob Backlund, American Pro Wrestler.
 Bob Barker, an American TV game show host
 Bob Bryan, a professional American tennis player.
 Bob Bryar, the current drummer for My Chemical Romance
 Bob Burnquist, professional skateboarder
 Bob Carolgees, British comedian and puppeteer
 Bob Carr, Australian politician and Premier of New South Wales
 Bob dela Cruz, a Filipino contestant in Pinoy Big Brother, Season 1
 Bob Clotworthy, American diver
 Bob Dole, American politician
 Bob Dylan, American singer-songwriter
 Bob Geldof, former lead singer of the Boomtown Rats, organiser of Live Aid concerts 
 Bob Hope, an American comedian
 Bob Hoskins, British actor
 Bob Marley, a Jamaican musician
 Bob McGrath, American actor
 Bob Monkhouse, British stand-up comedian and television presenter
 Bob Newhart, an American actor
 Bob Ross, American painter
 Bob Saget, an American comedian
 Bob Sinclar, a French DJ
 Bob Stupak, an American entrepreneur, gambler and politician
 Bob Weir, former rhythm guitarist of the Grateful Dead
 Bob Woodward, an American journalist