He is a hyperactive, neurotic nerd with a large frontal cowlick who is obsessed with banal pop culture, especially Wheel of Fortune and its host, Pat Sajak. He also loves to play the triangle, which for him consists of playing a recorded musical piece, striking the triangle once, and then wildly dancing to the recording. His catch phrases include "I must say", "totally decent", "makes me completely mental," and "give me a break". One 1985 SNL skit featured Ed's look-alike Uncle Basil, played by TV sportscaster Howard Cosell.
The character originated with Short as an unnamed school parent in sketch on The Second City stage. Originally, his hair was simply very greasy and unkempt, but another cast member joked offstage that the height of the hair seemed to increase with each performance. As an inside joke, Short started greasing it straight up.
Ed Grimley also made an appearance on the Martin Short Show in 1994, in a spoof of the film Dave. The President of the United States is an exact double of Ed Grimley, right down to the shark-tooth hairstyle. He hires Grimley to be his double and run the country while he enjoys time with his mistress. Unfortunately for Ed, the President suffers a heart attack and Ed Grimley is forced to cover up the tragedy by now having to pretend he is the president. Sally Field guest-starred as the First Lady who does not realize what has happened. Ed Grimley is scared to deal with her, as he is presumably unmarried and may have difficulties being in relationships with women.
After achieving popularity on SNL, Grimley became a cartoon character on Hanna-Barbera's animated show The Completely Mental Misadventures of Ed Grimley (1988). In each episode, Grimley would have an adventure of some sort, interspersed with science lessons from The Amazing Gustav Brothers, named Roger and Emil, and a live-action segment with a "scary story" presented as a show-within-a-show by Grimley's favourite television host, Count Floyd (Joe Flaherty, also reprising his SCTV character; he also has a voice appearance as the sea captain in "Moby is Lost".) Hanna-Barbera sponsored an "Ed Grimley Look-a-like Contest" midway through the first season, which was won by 10-year-old Matt Mitchell from Des Moines, Iowa.
- "Tall, Dark & Hansom" (Ed fills in for his cousin, driving a hansom cab, and ends up in a horse race)
- Ed's Debut (Ed mistakenly thinks he is asked to play triangle for the philharmonic and on the way to the concert hall is arrested and imprisoned for a bank robbery he did not commit)
- "E.G., Go Home" (Ed took his friend Wendall to an amusement park with a rocket ride that actually takes them to another planet which is ruled by an alien who sounds like Bette Davis)
- "Ed's In Hot Water" (Looking after the apartment building for his landlady Fiona Freebus while she and her husband are on vacation, Ed causes a huge flood which sends him out to sea where he meets up with long, lost aviatrix Hillary Black Smythe, who acts and sounds like Kate Hepburn)
- Crate Expectations (Ed gets trapped in a crate while trying to get a birthday present for Miss Malone)
- Grimley, P.F.C. (In the wrong line to return a library book, Ed joins the army and ends up second banana to a Bob Hope-like USO performer)
- Moby Is Lost (Moby, Ed's pet goldfish, is missing and Ed hires a television-obsessed sea captain to lead the search)
- Good Neighbor Ed (Ed wins a contest but to fulfill the contest rules he needs to take a picture of all of his neighbors.)
- Driver Ed (Miss Malone needs to learn how to drive and calls upon Ed to teach her)
- Blowin in the Wind (Ed is caught up in the same tornado that sends Dorothy to Oz, only he ends up on the farm with Aunt Em and Uncle Henry where a travelling summer stock show, with a Jerry Lewis-like director, are hoping for a shot at Broadway. The title is a reference to the classic folk song Blowin' in the Wind).
- Eyewitness Ed (Needing hot dog weiner franks for a party, Ed makes a run to the store, which resembles the Bates Motel, and witnesses Der Bingle rob the proprietor for which he testifies and must go into the witness protection program)
- Eddy, We Hardly Know Ye (Needing his tonsils out, Ed goes into the hospital where his roommate is a werewolf.)
- The Irving Who Came To Dinner (Irving Cohen pays a visit and helps Ed reveal a couple of hucksters)
Guest stars include Jonathan Winters as Ed's landlord Leo Freebus, Andrea Martin as Leo's wife Fiona, and Catherine O'Hara as his neighbor Miss Malone, who were semi-regulars on the show. Other guest stars included:
- Dave Thomas (USO performer in "Grimley PFC").
- Eugene Levy (proprietor in "Eyewitness Ed")
- Christopher Guest (the werewolf in "Eddy, We Hardly Knew Ye")
- Ringo Starr as a man who is regularly struck by lightning
- Spanish: Las Locas Aventuras y Desventuras de Ed Grimley (in which "I must say" is translated as "Digo yo, ¿no?".)