Katie Walder as "Shannon" with Neil Patrick Harris on 'How I Met Your Mother'.

Seth Green, Eric Mabius, and Katie Walder in Franklin & Bash (2011)

Bianca Kajlich and Katie Walder in Rules of Engagement (2007)

Neil Patrick Harris and Katie Walder in How I Met Your Mother (2005)

Vincent Kartheiser, Katie Walder, and Collette Wolfe in Mad Men (2007)

Katie Walder at the premiere for “Shazam! Fury of the Gods”

Katie Walder at the ‘Shazam! Fury of the Gods’ premiere

Still of Katie Walder as "Sherry" on 'Mad Men'.

Still of Katie Walder and Alison Brie on 'Mad Men'.

Nick Kroll & Katie Walder and "Kroll Show"

Brad Rowe, Tina Holmes, Katie Walder, Trevor Wright, Jackson Wurth, and Ross Thomas in Shelter (2007)