Flash Thompson has appeared in several other media adaptations of Spider-Man, usually in his earlier bullying incarnation.
In a very early issue (Amazing Spider-Man no. 8), Flash and Peter square off for a boxing match in the school gym. Initially expecting an easy victory, Flash is astonished to discover that he simply can't lay a hand on his opponent (due to Peter's enhanced speed and reflexes), and a single tap from Parker's fist knocks him clear out of the ring. Significantly, after this episode, Flash's bullying is restricted mostly to verbal harassment, suggesting that he was secretly wary of Peter's fighting prowess. Over the next few years, as the two become rivals for Liz Allan's affections, Flash is only willing to confront Peter when he (Flash) is surrounded by his friends. Peter, for his part, begins to laughs off his threats with good-natured comebacks (much to Flash's annoyance). This subtle reversal of their positions is typical of Lee-Ditko character developments in the title. At a much later point, Flash's back story is retconned to imply that he was physically abused by his alcoholic father, often called Harrison Thompson, leading to his violent, bullying nature; in a sense, making Peter a victim of Flash's misplaced anger.
Towards the end of Ditko's run on the title, Flash was employed mainly as comic relief, more a local buffoon than a serious threat. Major changes in his personality took place subsequent to issue 39, when Johnny Romita (Sr) took over as the strip's artist. Intitially working closely with writer/editor Stan Lee, Romita transformed Flash into a more sympathetic character, making him an impulsive but likable college athlete. His clean-cut image was similarly emphasized to give him an "All-American" persona - a wholesale improvement over the bullying jock he was in his previous appearances.
After Flash enters Empire State University, his relationship with Peter becomes progressively less hostile. While the two still trade the occasional insult, Flash has grown to respect Peter's intelligence and is surprised by his popularity with the girls (particularly Gwen Stacy, and Mary Jane Watson). Perhaps most tellingly, both are friends with Harry Osborn, whose presence serves to defuse the tension between the former rivals. Although genuine friendship is still a long way off, the outright hostility that characterised their relationship is a thing of the past.
While in university, Flash enlists with the United States Army and serves in the Vietnam War (although, due to Marvel's sliding time scale, this was later retconned to some unspecified overseas conflict). This was a further elaboration of Flash's "All-American" persona; unlike many students of the time, Flash was never conscripted - instead, volunteers for service of his own free will. Although Flash was absent from the strip for months at a time, his frequent stateside visits kept him familiar with the readers.
While in Vietnam, Flash's unit bombs an ancient temple whose acolytes had earlier sheltered Flash when he was wounded. Flash tried and failed to stop them.
When he returns to America, he drops his antagonism toward Peter. Peter, in turn, begins to respect Flash's newfound maturity and the two become close. However, Flash soon finds himself tailed by mysterious assassins, former acolytes of the temple who think that Flash had betrayed them. Spider-Man holds off the assassins long enough for Flash to explain his side of the story. Sha Shan, the leader of the assassins, forgives Flash and even dates him for a while, but leaves him when she finds out he is cheating on her. Flash's tour of duty profoundly changed him from a reckless and immature youth to a tormented and conflicted man. Finding no comfort in his military decorations, Flash turned to alcohol for years.
When Sha Shan is attacked by the Hobgoblin, Flash makes the mistake of insulting the villain on television. The Hobgoblin takes his revenge by abducting Flash and framing him as the Hobgoblin's true identity. Spider-Man is aghast that his old friend is a villain, but Flash is legally exonerated when the Hobgoblin's true identity is revealed.
Thompson has relationships over the years with several of the same women as Peter. In high school, he dates Liz Allan. One of the reasons Flash bullies Peter is because he secretly fears that Liz prefers Peter to him. Flash is briefly romantically involved with Mary Jane Watson in college. He has a long, on-and-off relationship with Betty Brant. Felicia Hardy (the Black Cat) dates him in order to make Peter jealous, but is surprised when she actually falls in love with him. Finally Flash breaks up with her, as he feels he can't keep up with her high-speed lifestyle. After he and Peter put their antagonism behind them and become friends, Flash serves as best man at Peter and Mary Jane's wedding.
After a bout severe depression over the course of his life and his inability to reconnect with Betty, Flash went drunk-driving and was badly injured in a crash. Soon afterwards, his life began a dramatic upswing when Norman Osborn, the Green Goblin, offered him a job at Oscorp as his personal aide in order to annoy Peter Parker; not knowing the reasons behind this, Flash became loyal to Norman for giving him a second chance and turning his life around. During this time, Flash meets the hero Prodigy, not realising he is also Spiderman in disguise. Later, as part of a plan of driving Spider-Man to murderous violence by attacking his family and friends, Osborn kidnaps Flash (under the pretense of picking him up from an Alcoholics Anonymous meeting), force-feeds him whiskey and has him crash a truck into Midtown High School, where Peter works. Flash survives, thanks to his excellent physical condition, but he suffers severe brain damage that leaves him in a coma. Liz Allan Osborn, although widowed and raising her son Normie all on her own, becomes Flash's caretaker, and hires a full-time nurse to care for him. Peter, blaming himself for what happened to Flash, makes a point of visiting his friend as often as he can.
Peter learns that Flash had awakened from his coma during the "Spider-Man: The Other" story arc. Flash takes a job as the mens gymnastics and interpretive dance coach at Midtown High School, where Peter teaches science. However, Flash suffers from severe memory gaps. When meeting Peter again, he treats him like a nerd and picks on him, as he did in their high school days. In The Amazing Spider-Man #533 Flash watches the news reports of Spider-Man unmasking, but dismisses it as a trick, as "Puny Parker" couldn't be Spider-Man. When Peter returns to work as a teacher, Flash still refuses to believe it, even after Peter uses his abilities in an impromptu dodgeball game that blackens both of Flash's eyes. Afterward, Flash seems to flirt with the school nurse, Miss Arrow. Finally believing Peter after witnessing his battle with Daniel Berkhart and Francis Klum, both battling for the Mysterio namesake, he forms a renewed alliance with Peter. After sharing a kiss with Miss Arrow (who earlier has, unbeknowst to him, displayed stingers similar to that of the Other), he's convinced by her to talk Peter Parker into keeping his teacher role.
Flash briefly appeared at the conclusion of the controversial One More Day story arc, attending a welcome home party for the newly resurrected Harry Osborn. Due to Mephisto's magic, Flash, like the rest of the world, no longer remembers that Peter is Spider-Man. He seems to just be an associate of Harry and Peter and not one of their good friends.
M.J.: I don't want to be with you anymore. Here's your ring.
(She hands him his ring.)
Flash: You know what? Whatever. Your loss.