In 1960, ABC experimented with not one, but two animated prime time series. The Bugs Bunny Show spent 2 seasons as a night-time series before shifting to Saturday mornings, where Bugs would be a mainstay for an amazing 38 years, easily the longest-running Saturday morning franchise. Everyone knows the equally legendary theme song, "This is It", as performed by Bugs & Daffy Duck (both voiced, of course, by Mel Blanc). Here's a black & white clip from the original 1960 series.
Bugs shifted back & forth between ABC & CBS throughout his 40 years on network television, with CBS adding a series of prime-time specials, even giving Bugs a prime-time series berth as a summer replacement one year. Veteran announcer Dick Tufeld was the series' original announcer, as he handled those duties for many of WB's live-action series of the period, including Hawaiian Eye.
In 1968, Bugs moved to CBS for the first time, as the "Tiffany of the Networks" fused his series together with that of the Road Runner to form a 1 hour series, which lasted initially until 1971, when the fast-feathered Road Runner moved to ABC. Bugs would return there in 1973 for 2 seasons, then back to CBS for 11 (1975-86), then back to ABC for the final 14 seasons. During his third & final ABC run, Tweety became the co-featured star, replacing the Road Runner, and this was even with Tweety starring in an all-new series on WB during the late 90's that was previously covered. Beginning with 1968's Bugs Bunny-Road Runner Hour, different announcers took over the introduction, including Danny Dark (Super Friends) during the early 80's.
I should mention that "This is It" was composed by WB's in-house songwriting team of Jerry Livingston & Mack David, who also composed themes to several of the studio's live-action shows.
After WB had shipped Bugs and pals over to Cartoon Network, the cabler decided to devote a 3 hour block at one point on Saturdays to try to recapture the magic, but it didn't last. As it is, there is a devoted fan base that is pleading in vain with CN's current programming head, Stuart Snyder, to put Bugs, Daffy, and company back on Saturdays or anywhere else on the schedule, but as of now, they'll have to settle for the forthcoming Looney Tunes Show, due to air in prime time soon.