Spike could mean:
 Nail, especially one more than 100mm (4 inches) long
 Rail spikes used to secure railroad rails to the wooden ties
 Spiked shoes worn by athletes, which provide more traction (similar to cleats)
 An adolescent male deer or male elk
 The Spike is a widely used nickname for the Spire of Dublin, a massive needle-like structure erected in Dublin in 2003
 Spike TV, a cable network that caters to a young male demographic (originally known as TNN, The National Network, or The Nashville Network)
 Spike missile, an Israel-developed guided anti-tank missile
 Spike bayonet, chiefly used on early muskets
 Voltage spike, or electrical surge
 The action potential which transmits signals along a nerve axon is often called a spike
 Spike is a botanical term for an unbranched, indeterminate inflorescence with sessile flowers arranged along the axis
 Spike (company), a video game company

Media with Spike in the title include:
 The Spike (Borchgrave/Moss), a 1980 novel by Arnaud de Borchgrave, former editor of The Washington Times
 Spike of Bensonhurst, a 1988 movie directed by Paul Morrisey
 Spike (Elvis Costello album), a 1989 album by Elvis Costello
 The Spike (1997), a 1997 book by Damien Broderick
 Spike (Puffy AmiYumi album), a 2001 album by Puffy AmiYumi

A number of famous people are named Spike, including:
 Spike, a newcomer Romanian rapper promoted by Parazitii
 Spike Lee, a filmmaker
 Spike Jonze, a filmmaker
 Spike Jones, a satirist
 Spike Milligan, a satirist
 Spike Robinson, a jazz musician
 Spike Slawson, a punk vocalist and bassist of the Swinging Utters and Me First and the Gimme Gimmes
 Matt Hyson (aka Spike Dudley), former professional wrestler
 Spike (porn star), a gay pornography actor
 Spike Feresten, television writer and talk show host
 Spike Xavier, Lead Singer of Nu-Metal band Corporate Avenger
 Spike, a Welsh musician, co-founder of Z Block Records, Reptile Ranch and Weekend
 Spike O'Donnell, famous Irish/American gangster from Chicago
A number of fictional characters have been named Spike, including:
 Spike, a main playable character in the Ape Escape video game series
 Spike Spiegel, from the Japanese anime Cowboy Bebop
 Spike (Buffyverse), a vampire
 Spike, Fonzie's cousin in Happy Days
 Spike Fumo, in Spike of Bensonhurst
 Christine "Spike" Nelson, in the Degrassi series
 Spike Thomson, in Press Gang
 Spike, a member of the Screws Gang in Medabots
 Spike Lester, a character on the soap opera Passions
 The Spike (Marvel Comics), a member of the X-Statix
 Spike Freeman, another character in Marvel Comics' X-Statix/X-Force
 Spike (The Land Before Time), a young stegosaurus in The Land Before Time film series
 "Spike" Stoker, a supporting character from Jasper Fforde's Thursday Next books
 Joshua "Spike" Cohen, a Jew from Tom Robbins' novel Skinny Legs and All
 Spike, a character originating in Super Mario Bros. 3 who launches spiked mace balls at the player
 Spike, the boss of the Midday Gardens world in the Spyro: Year of the Dragon video game
 Spike, a character in the DC Comics comic book Sugar and Spike
 Spike Lavery, a character on All My Children, he the son Kendall and Ryan
 Father Spike, a high-church parish priest who is mentioned in C.S. Lewis' book The Screwtape Letters
 Spike, Roger Wilco's alien pet in Space Quest V: The Next Mutation
 Spike, a porcupine from the movie Over the Hedge
 Spike Witwicky, a character from the Transformers TV cartoon series and comic books
 Spike (NX Files), a fictional character in an action-adventure web-show called NX Files
 Michelangelo 'Spike' Scarlatti, a fictional character in the Canadian TV series Flashpoint

A number of cartoon dogs have been named Spike:
 Spike (Ace Ventura), Ace Ventura's dog in the motion picture Ace Ventura: When Nature Calls
Spike (Goofy Movie)
Spike (Peanuts), Snoopy's brother in Peanuts
 Spike (Tom and Jerry), Tom's and the other cats' nemesis in the cartoon series Tom and Jerry
 Spike the Bulldog and Chester the Terrier, in the Warner Bros. Looney Tunes and Merrie Melodies series of cartoons
 Spike, the family pet in Rugrats
 Spike, Heathcliff's nemesis in the comic strip and animated series Heathcliff
 Spike, Droopy's nemesis in Tex Avery's Droopy Dog theatrical cartoon series

As a place name, Spike may refer to:
 Spike is the former name of a village in Derbyshire now known as Poolsbrook

In sports, Spike may refer to:
 A spike is an offensive attack in volleyball
 Spiking in American football is to throw the ball forcefully and intentionally into the ground
 In Track and Field and cross country running, spiking an opponent (or sometimes, inadvertently, a team mate) is to kick them with the metal spikes in the bottom of the runner's shoe