I Wanna Be Like You

TV characters who've dressed as/like each other:

After getting über drunk at a birthday party thrown for him at the Simpsons' house, Barney Gumble descended the stairs dressed as Marge Simpson in The Simpsons.

When he was told to dress as somebody he admired, Alan Shore (James Spader) turned up at the office costume party dressed as his colleague Shirley Schmidt (Candice Bergen) in Boston Legal.

Special Agent Seeley Booth (David Boreanaz) imitated his co-workers when he dressed as a "Squint" (someone with a very high IQ and basic reasoning skills) in Bones.

As part of a "Freaky Friday social experiment" to try to prove who has it harder in America, women or black men, Jenna Maroney (Jane Krakowski) and Tracy Jordan (Tracy Morgan) switched roles in 30 Rock.

I Am Wonder Woman, Hear Me Roar

TV characters who've donned Wonder Woman costumes:

Miss Piggy transformed into "Wonder Pig" in order to fend off a giant chicken in a superhero themed episode of The Muppet Show, which featured a guest appearance by Lynda Carter (who played Wonder Woman in the 70s TV show Wonder Woman).

Comic book nerd Seth Cohen (Adam Brody) thought he was going to pass out when Summer Roberts (Rachel Bilson) put on a Wonder Woman costume as a Christmas Chrismukkah present for him in The OC.

After accidently killing the man he believed to be his father in a unicycle stunt gone wrong, Peter Griffin sported a Wonder Woman costume before heading to Ireland to try to find his real father in Family Guy.

Special Agent Seeley Booth (David Boreanaz) thought Dr. Temperance "Bones" Brennan (Emily Deschanel) looked wonderful when she dressed up as Wonder Woman for Halloween in Bones.

Costume Drama

TV characters who like to play dress up:

Sam Weir (John Francis Daley) and his friends Neal Schweiber (Samm Levine), Bill Haverchuck (Martin Starr) and Harris Trinsky (Stephen Lea Sheppard) dressed up to go trick-or-treating in Freaks and Geeks.

Alan Shore (James Spader) and Denny Crane (William Shatner) dressed as flamingos for their office Halloween party in Boston Legal and referenced 80s teen film Pretty in Pink (which James Spader appeared in) when Alan said "Denny, you look pretty in pink".

Dr. Temperance "Bones" Brennan (Emily Deschanel) and Special Agent Seeley Booth (David Boreanaz) went undercover as a Russian knife-throwing act named Buck and Wanda Moosejaw in order to investigate the murder of conjoined circus twins in Bones.

CIA double agent Sydney Bristow (Jennifer Garner) kicked ass and looked good doing it as she donned various disguises while attempting to bring down SD-6, and other organisations that threatened the security of the free world in Alias.