Final answer:
Ellen DeGeneres's character on the sitcom 'Ellen' came out as gay in 1997, mirroring DeGeneres's real-life coming out, marking a significant moment for LGBTQ+ representation on television.
Step-by-step explanation:
According to lecture, the actor who came out to the world as part of the plot of their sitcom, making them one of the first openly gay actors and characters on television, was Ellen DeGeneres. Her character Ellen Morgan on the sitcom 'Ellen' came out in a 1997 episode titled 'The Puppy Episode', which was a significant moment in TV history for LGBTQ+ representation. This moment mirrored DeGeneres's own coming out in real life, as she also announced that she was a lesbian on 'The Oprah Winfrey Show' and in Time magazine.