Teen characters who have a friend (sometimes a "best friend") who is of the other sex, but not a ("romantic") relationship
This seems to have become a cliché beginning in the late 1980s,
perhaps a "convenient" device to avoid all-boy or all-girl casts.
NOTE: these "best friends" are always written as heterosexual,
not just assumed so, but expressed in actions and words
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The Adventures of Pete and Pete (Nickelodeon, 1993-1996)
Big Pete Wrigley (Michael C. Maronna) and Ellen Josephine
Hickle (Alison Fanelli) [both about 14]
Little Pete Wrigley (Danny Tamberelli) and Nona F. Mecklenberg
(Michelle Trachtenberg) [both about 11]
Quote actually posted on www.imdb.com/title/tt0105933/quotes:
"Older Pete Wrigley: 'She's a girl, and she's my friend, but she's
not my girlfriend.'" (This is the stereotypical statement, often
found in scripts that use the device of boy/girl "best friends".)
Little Pete and Nona's friendship is introduced in the first episode
of Season 2 ("Grounded for Life" [1994]); at first she's just a new neighbor.
Neither brother ever has close male friends outside the family.
In "Time Tunnel" (23 October 1994), Big Pete asks Ellen out on a date,
so that he can find out once and for all if they are "just friends" or
more than friends. The date does not work out as a romantic, encounter, so they
conclude that "being friends again" is all they want. (Ellen, however,
kisses Big Pete on the lips as they say goodbye for the evening.)
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The Big Bang Theory (CBS, 2007-present)
The characters in this show are adults with Ph.D.s, but often are played
as if they were nerdy adolescents. Dr Sheldon Cooper (Jim Parsons) is
notoriously asexual, utterly capable of having relationships with women
or men without any thought of sexuality getting in the way. His close
male friends are all actively seeking female partners, and when
Sheldon strikes up a relationship with Dr Amy Farrah Fowler (Mayim Bialik),
he is continually explaining to everyone that she is "a girl",
and "a friend", but not a "girlfriend". (At this
writing, the show is still developing with new episodes; time will tell
whether the show's writers will change Sheldon's lifelong abstinence
pattern.)
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Clarissa Explains It All (Nickelodeon, 1991-1994)
Clarissa Darling (Melissa Joan Hart) and Sam Anders (Sean O'Neal),
about 14 in Season 1.
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Even Stevens (Disney, 1999-2003)
Louis Stevens (Shia LaBeouf) and Tawny Dean (Margo Harshman), along
with Alan Twitty (A.J. Trauth) and Tom Gribalski (Fred Meyers).
They are classmates, about 12 in the first season of the show.
In the final episodes, Louis and Tawny change their "best friend"
relationship into a romantic one (always a tempting plot device for writers of
teen-themed shows).
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The Golden Palace (NBC, 1992-1993)
"One Old Lady to Go", 9 October 1992
Oliver Webb (Billy L. Sullivan) and Amy, a girl at school (not seen).
Cast members (adults) tease Oliver (about 12), making kissy noises and
taunting, "Someone's got a girlfriend" when they find out he wants to earn
$50 for a trip to WaterWorld, when admission only costs $25. Oliver:
"Hey, cut it out, OK? She's just a friend who happens to be a girl."
Later, Oliver asks Roland Wilson (Don Cheadle), his guardian, if it's
"normal" to like a girl just as a friend. Roland (predictably), says
yes, it's perfectly normal, and cautions him not to rush into
adulthood: "Don't ever be in a hurry to grow up. You're just a kid for
a little while. Enjoy it."
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Jeremy Fink and the Meaning of Life, 2011 film
Jeremy Fink (13)(Maxwell Beer) narrates the film's trailer, in which he
introduces himself and his "best friend" Lizzy Muldoun (Ryan
Simpkins). "Yes, my best friend is a girl, and no, I don't have a crush
on her", he informs us, with a slight air of annoyance.
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Ned's Declassified School Survival Guide (Nickelodeon, 2004-2007)
Ned Bigby (Devon Werkheiser) and Jennifer Ann 'Moze' Mosely (Lindsey Shaw), along
with Simon 'Cookie' Nelson-Cook (Daniel Curtis Lee). They are classmates at
James K. Polk Middle School, 13 years old in Season 1.
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The Odyssey (Canada, 1992-94)
Jay Ziegler (Illya Woloshyn) and Donna Archipenko [Alpha in the Downworld]
(Ashley Rogers aka Ashleigh Aston Moore), about 11 when series starts,
mid-teens at end. In "The Cauldron" (14 November 1994), When Sierra Jones
(Andrea Nemeth) asks Jay at a party (near the end of the series, when
they're mid-teens), "How's your girlfriend?", he replies, "Donna?
She's just my friend. You can have a friend that's a girl without
her being your girlfriend." [Sierra Jones comments, "Hm. Well, it's
not so easy just to be friends with a boy."]
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Oliver Beene (Fox, 2003-04)
Oliver (Grant Rosenmeyer) and Joyce (Daveigh Chase), along with Michael
(Taylor Emerson), who is portrayed as "pre-gay". They are classmates,
about 11 years old in this single-season show which takes place in 1962.