Problem: Background: Kermit the Frog is a Muppet character and Jim Henson's most well-known creation. Introduced in 1955, Kermit serves as the straight man protagonist of numerous Muppet productions, most notably Sesame Street and The Muppet Show, as well as in other television series, films, specials, and public service announcements through the years. Henson originally performed Kermit until his death in 1990; Steve Whitmire performed Kermit from that time up until his dismissal from the role in 2016.
Context: Jim Henson originated the character in 1955 on his local television series, Sam and Friends. Brian Henson described his father's performance as Kermit as "coming out of his own personality--was a wry intelligence, a little bit of a naughtiness, but Kermit always loved everyone around and also loved a good prank." He continued to perform the character until his death in 1990. Henson's last known performance as Kermit was for an appearance on The Arsenio Hall Show to promote The Muppets at Walt Disney World. Henson died twelve days after that appearance. Following Henson's death, veteran Muppet performer Steve Whitmire was named Kermit's new performer. In 2017, Whitmire seemed to imply in a blog post that Jim Henson had asked him to assume the role before he died, though Jim's daughter Cheryl Henson claimed Brian had selected him after Jim's death. Whitmire's first public performance as Kermit was at the end of the television special The Muppets Celebrate Jim Henson in 1990. He remained Kermit's principal performer until 2016. Disney announced that Matt Vogel would be taking over as the performer and voice for Kermit on July 10, 2017. Whitmire later revealed that he had not chosen to voluntarily leave the role, but rather, had been recast by Muppet Studios in October 2016. In an interview with The Hollywood Reporter later in July 2017, Whitmire elaborated he was fired for two reasons: long-term creative disagreements over Kermit's characterization and prolonged labor union negotiations that delayed his involvement in Muppet-related productions. For a brief demonstration at MuppetFest (a 2001 Muppet fan convention), Muppet performer John Kennedy performed Kermit opposite Whitmire's performance of young Kermit (from Kermit's Swamp Years). Kennedy also performed Kermit for Muppets Ahoy!, a 2006 Disney Cruise Line stage show (though Whitmire performed Kermit for the first few shows). Muppet performer Artie Esposito briefly performed Kermit in 2009 for a few personal appearances (an appearance on America's Got Talent, an appearance at the MTV Video Music Awards, and at the 2009 D23 Expo with Rowlf the Dog as part of a tribute to Jim Henson). Voice actor Frank Welker provided the voice of Baby Kermit on the animated Saturday morning cartoon, Muppet Babies. He also provided the voice of an adult Kermit for a short-lived spin-off, Little Muppet Monsters.
Question: How long did he perform?
Answer: He remained Kermit's principal performer until 2016.

Background: Steel (John Henry Irons), also known as the Man of Steel, is a fictional character, a superhero in the DC Universe. Introduced in 1993 as one of several replacements for the then-deceased Superman, Steel continued to be an independent superhero after his inspiration's resurrection. He received his own ongoing series which saw him move from Metropolis to Washington, D.C. and join the Justice League of America in Grant Morrison's JLA. He later mentored his niece Natasha who became a superheroine herself.
Context: In 1997, a feature film was produced based on this version of the character. The film Steel stars professional basketball player Shaquille O'Neal in the title role and Judd Nelson as a new villain named Nathaniel Burke. The film was originally designed to be a spin-off of the new Superman film that used the "Death of Superman" storyline that first introduced the character in the comics. The project languished in development hell for so long the spinoff moved forward without the film it was to be attached to. The movie (released on August 15) was considered a flop both critically and financially. Steel was produced for an estimated $16,000,000 but grossed $1,686,429 at the box office. A very young John Henry Irons appears in the animated film Justice League: The New Frontier reading a comic book nearby the gravestone of the "DC: The New Frontier" version of John Wilson, also known as John Henry, who is reportedly killed in the film. John Henry Irons appears in Justice League: Throne of Atlantis, voiced by Khary Payton. He is seen wielding a hammer and is seen defending a colleague from an Atlantean before he is saved by Superman. An alternate universe version of John Henry Irons appears in Justice League: Gods and Monsters, voiced again by Khary Payton. He is depicted as a scientist who is a member of LexCorp's "Project Fair Play." John was discussing with the other scientists involved (consisting of Will Magnus, Michael Holt, Karen Beecher, Pat Dugan, Kimiyo Hoshi, Emil Hamilton, Thomas Morrow, and Stephen Shin) before they are all killed by the Metal Men with the exception of Will Magnus (who secretly orchestrated the attack).
Question: Who is Steel's main enemy?
Answer:
Judd Nelson as a new villain named Nathaniel Burke.