|The Olsen Twins|
|Full Name|| Mary-Kate Olsen|
|First Appearance (Barney and the Rocko Squad)||Barney's Visit|
|Barney and the Rocko Squad Portrayer|| Mary-Kate Olsen (Mary-Kate)|
Ashley Oslen (Ashley)
- "I could do that list forwards, backwards, and upside-down!!!"
- — Mary-Kate telling her sister how she could do a party list.
- "Sleeping bags! Check! Pillows! Check! CDs, video games, popcorn! Check, check, and check! Invitations? UH-OH..."
- — Mary-Kate and Ashley going over their party list.
- "I NEVER WANT TO HEAR THE WORDS "HOMEWORK" AND "PARTY" IN THE SAME SENTENCE!!!"
- — Mary-Kate, angry with her sister.
Mary-Kate and Ashley Olsen, referred to Evil-Man as Chatty Kathy and Cannonizer, respectively, are live actresses. Ashley, however, is not to be confused with Ashley One and Two. They visit the Rocko Squad near most of their lives. They are unaware that Spader has a crush on them (he appears in every Barney and the Rocko Squad episode since their debut).
Neither Mary-Kate nor Ashley Olsen can help their sleeping. The only known times they slept prior to Barney and the Rocko Squad was during their Sleepover Party in in 1995, their Campout Party in 1998, and their Christmas Party in 1997 (most likely due to Santa). When Evil-Man notices this, he will be very mad.
Mary-Kate's voice actress is herself, and that is also true with her twin sister.