“How I Met Your Mother”'s 25 most memorable guest stars

“How I Met Your Mother”'s 25 most memorable guest stars

These celebrity appearances were legen — wait for it — dary.Britney Spears as Abby, Kyle MacLachlan as the Captain, and James Van Der Beek as Simon on 'How I Met Your Mother'Credit: Monty Brinton/CBS via Getty; Richard Cartwright/CBS via Getty; Cliff Lipson/CBS via GettyHow I Met Your Mother became one of the only traditional multi-camera sitcoms to find long-term success in the wake of Friends. The CBS comedy, which explored the love lives of T…