It is common knowledge that Lucy and Ethel played best friends on "I Love Lucy", and then again on "The Lucy Show". As may be expected, they became best friends in real life as well.
I have always loved the comraderie and love they have with and towards each other, and striven for that in my relationships with girlfriends. For me that started at an early age, right around the time I discovered "I Love Lucy". One of my best friends through childhood (who is now my sister, Emily) and I were a lot like Lucy and Ethel. Emily never had the same crazy infatuation with "I Love Lucy" that I did, but she did get pretty hooked for a time, and I think without realizing it, we began to model our relationship after Lucy and Ethel. We would scheme together, go against her brother, Elliott, together, and get into all sorts of shennanigans I think Lucy and Ethel would be proud of. We even dressed up as them for Halloween when we were 13 (even though Emily as a dark brunette wore a ridiculous blond wig for Ethel and I had a very un-Lucy-like mouth full of braces), which was a blast. (I dressed up like Lucy again when I was around 16 or 17, this time with a wash out red dye in my hair and a fake perm).
I daresay Lucy and Ethel inspired countless pairs and groups of girlfriends to follow their lead when it came to comraderie, support, and love. "I Love Lucy" has many legacies, but I think Lucy and Ethel's is in a league of it's own.